Fix exception causes all over the codebase (#205)

gymnasium/envs/box2d/bipedal_walker.py

@@ -21,10 +21,10 @@ try:
         polygonShape,
         revoluteJointDef,
     )
-except ImportError:
+except ImportError as e:
     raise DependencyNotInstalled(
         "box2D is not installed, run `pip install gymnasium[box2d]`"
-    )
+    ) from e
 
 
 if TYPE_CHECKING:
@@ -621,10 +621,10 @@ class BipedalWalker(gym.Env, EzPickle):
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[box2d]`"
-            )
+            ) from e
 
         if self.screen is None and self.render_mode == "human":
             pygame.init()

gymnasium/envs/box2d/car_dynamics.py

@@ -17,10 +17,10 @@ from gymnasium.error import DependencyNotInstalled
 
 try:
     from Box2D.b2 import fixtureDef, polygonShape, revoluteJointDef
-except ImportError:
+except ImportError as e:
     raise DependencyNotInstalled(
         "box2D is not installed, run `pip install gymnasium[box2d]`"
-    )
+    ) from e
 
 
 SIZE = 0.02

gymnasium/envs/box2d/car_racing.py

@@ -15,20 +15,20 @@ from gymnasium.utils import EzPickle
 try:
     import Box2D
     from Box2D.b2 import contactListener, fixtureDef, polygonShape
-except ImportError:
+except ImportError as e:
     raise DependencyNotInstalled(
         "box2D is not installed, run `pip install gymnasium[box2d]`"
-    )
+    ) from e
 
 try:
     # As pygame is necessary for using the environment (reset and step) even without a render mode
     #   therefore, pygame is a necessary import for the environment.
     import pygame
     from pygame import gfxdraw
-except ImportError:
+except ImportError as e:
     raise DependencyNotInstalled(
         "pygame is not installed, run `pip install gymnasium[box2d]`"
-    )
+    ) from e
 
 
 STATE_W = 96  # less than Atari 160x192

gymnasium/envs/box2d/lunar_lander.py

@@ -23,10 +23,10 @@ try:
         polygonShape,
         revoluteJointDef,
     )
-except ImportError:
+except ImportError as e:
     raise DependencyNotInstalled(
         "box2d is not installed, run `pip install gymnasium[box2d]`"
-    )
+    ) from e
 
 
 if TYPE_CHECKING:
@@ -618,10 +618,10 @@ class LunarLander(gym.Env, EzPickle):
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[box2d]`"
-            )
+            ) from e
 
         if self.screen is None and self.render_mode == "human":
             pygame.init()

gymnasium/envs/classic_control/acrobot.py

@@ -294,10 +294,10 @@ class AcrobotEnv(Env):
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
 
         if self.screen is None:
             pygame.init()

gymnasium/envs/classic_control/cartpole.py

@@ -219,10 +219,10 @@ class CartPoleEnv(gym.Env[np.ndarray, Union[int, np.ndarray]]):
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
 
         if self.screen is None:
             pygame.init()

gymnasium/envs/classic_control/continuous_mountain_car.py

@@ -205,10 +205,10 @@ class Continuous_MountainCarEnv(gym.Env):
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
 
         if self.screen is None:
             pygame.init()

gymnasium/envs/classic_control/mountain_car.py

@@ -180,10 +180,10 @@ class MountainCarEnv(gym.Env):
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
 
         if self.screen is None:
             pygame.init()

gymnasium/envs/classic_control/pendulum.py

@@ -180,10 +180,10 @@ class PendulumEnv(gym.Env):
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
 
         if self.screen is None:
             pygame.init()

gymnasium/envs/classic_control/utils.py

@@ -9,8 +9,9 @@ def verify_number_and_cast(x: SupportsFloat) -> float:
     """Verify parameter is a single number and cast to a float."""
     try:
         x = float(x)
-    except (ValueError, TypeError):
+    except (ValueError, TypeError) as e:
-        raise ValueError(f"An option ({x}) could not be converted to a float.")
+        raise ValueError(f"An option ({x}) could not be converted to a "
+                         f"float.") from e
     return x
 
 

gymnasium/envs/mujoco/mujoco_rendering.py

@@ -158,12 +158,12 @@ class OffScreenViewer(BaseRender):
         if self.backend is not None:
             try:
                 self.opengl_context = _ALL_RENDERERS[self.backend](width, height)
-            except KeyError:
+            except KeyError as e:
                 raise RuntimeError(
                     "Environment variable {} must be one of {!r}: got {!r}.".format(
                         "MUJOCO_GL", _ALL_RENDERERS.keys(), self.backend
                     )
-                )
+                ) from e
 
         else:
             for name, _ in _ALL_RENDERERS.items():

gymnasium/envs/phys2d/cartpole.py

@@ -141,10 +141,10 @@ class CartPoleFunctional(
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
         screen, clock = render_state
 
         world_width = self.x_threshold * 2
@@ -212,10 +212,10 @@ class CartPoleFunctional(
     ) -> RenderStateType:
         try:
             import pygame
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
 
         pygame.init()
         screen = pygame.Surface((screen_width, screen_height))
@@ -226,10 +226,10 @@ class CartPoleFunctional(
     def render_close(self, render_state: RenderStateType) -> None:
         try:
             import pygame
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
         pygame.display.quit()
         pygame.quit()
 

gymnasium/envs/phys2d/pendulum.py

@@ -90,10 +90,10 @@ class PendulumFunctional(
         try:
             import pygame
             from pygame import gfxdraw
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
         screen, clock, last_u = render_state
 
         surf = pygame.Surface((self.screen_dim, self.screen_dim))
@@ -161,10 +161,10 @@ class PendulumFunctional(
     ) -> RenderStateType:
         try:
             import pygame
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
 
         pygame.init()
         screen = pygame.Surface((screen_width, screen_height))
@@ -175,10 +175,10 @@ class PendulumFunctional(
     def render_close(self, render_state: RenderStateType) -> None:
         try:
             import pygame
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[classic_control]`"
-            )
+            ) from e
         pygame.display.quit()
         pygame.quit()
 

gymnasium/envs/registration.py

@@ -563,7 +563,7 @@ def make(
                 raise ModuleNotFoundError(
                     f"{e}. Environment registration via importing a module failed. "
                     f"Check whether '{module}' contains env registration and can be imported."
-                )
+                ) from e
         spec_ = registry.get(id)
 
         ns, name, version = parse_env_id(id)
@@ -647,7 +647,7 @@ def make(
                 f"You passed render_mode='human' although {id} doesn't implement human-rendering natively. "
                 "Gym tried to apply the HumanRendering wrapper but it looks like your environment is using the old "
                 "rendering API, which is not supported by the HumanRendering wrapper."
-            )
+            ) from e
         else:
             raise e
 

gymnasium/envs/toy_text/blackjack.py

@@ -235,10 +235,10 @@ class BlackjackEnv(gym.Env):
 
         try:
             import pygame
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[toy_text]`"
-            )
+            ) from e
 
         player_sum, dealer_card_value, usable_ace = self._get_obs()
         screen_width, screen_height = 600, 500

gymnasium/envs/toy_text/cliffwalking.py

@@ -208,10 +208,10 @@ class CliffWalkingEnv(Env):
     def _render_gui(self, mode):
         try:
             import pygame
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[toy_text]`"
-            )
+            ) from e
         if self.window_surface is None:
             pygame.init()
 

gymnasium/envs/toy_text/frozen_lake.py

@@ -340,10 +340,10 @@ class FrozenLakeEnv(Env):
     def _render_gui(self, mode):
         try:
             import pygame
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[toy_text]`"
-            )
+            ) from e
 
         if self.window_surface is None:
             pygame.init()

gymnasium/envs/toy_text/taxi.py

@@ -325,10 +325,10 @@ class TaxiEnv(Env):
     def _render_gui(self, mode):
         try:
             import pygame  # dependency to pygame only if rendering with human
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[toy_text]`"
-            )
+            ) from e
 
         if self.window is None:
             pygame.init()

gymnasium/experimental/wrappers/lambda_observations.py

@@ -272,10 +272,10 @@ class ResizeObservationV0(LambdaObservationV0):
 
         try:
             import cv2
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
-                "opencv is not install, run `pip install gymnasium[other]`"
+                "opencv is not installed, run `pip install gymnasium[other]`"
-            )
+            ) from e
 
         self.shape: Final[tuple[int, ...]] = tuple(shape)
 

gymnasium/utils/env_checker.py

@@ -113,7 +113,7 @@ def check_reset_seed(env: gym.Env):
             raise AssertionError(
                 "The environment cannot be reset with a random seed, even though `seed` or `kwargs` appear in the signature. "
                 f"This should never happen, please report this issue. The error was: {e}"
-            )
+            ) from e
 
         seed_param = signature.parameters.get("seed")
         # Check the default value is None
@@ -149,7 +149,7 @@ def check_reset_options(env: gym.Env):
             raise AssertionError(
                 "The environment cannot be reset with options, even though `options` or `**kwargs` appear in the signature. "
                 f"This should never happen, please report this issue. The error was: {e}"
-            )
+            ) from e
     else:
         raise gym.error.Error(
             "The `reset` method does not provide an `options` or `**kwargs` keyword argument."

gymnasium/utils/play.py

@@ -15,10 +15,10 @@ try:
     import pygame
     from pygame import Surface
     from pygame.event import Event
-except ImportError:
+except ImportError as e:
     raise gym.error.DependencyNotInstalled(
         "Pygame is not installed, run `pip install gymnasium[classic_control]`"
-    )
+    ) from e
 
 try:
     import matplotlib

gymnasium/utils/save_video.py

@@ -8,10 +8,10 @@ from gymnasium import logger
 
 try:
     from moviepy.video.io.ImageSequenceClip import ImageSequenceClip
-except ImportError:
+except ImportError as e:
     raise gym.error.DependencyNotInstalled(
         "MoviePy is not installed, run `pip install moviepy`"
-    )
+    ) from e
 
 
 def capped_cubic_video_schedule(episode_id: int) -> bool:

gymnasium/vector/async_vector_env.py

@@ -123,7 +123,7 @@ class AsyncVectorEnv(VectorEnv):
                 self.observations = read_from_shared_memory(
                     self.single_observation_space, _obs_buffer, n=self.num_envs
                 )
-            except CustomSpaceError:
+            except CustomSpaceError as e:
                 raise ValueError(
                     "Using `shared_memory=True` in `AsyncVectorEnv` "
                     "is incompatible with non-standard Gymnasium observation spaces "
@@ -131,7 +131,7 @@ class AsyncVectorEnv(VectorEnv):
                     "only compatible with default Gymnasium spaces (e.g. `Box`, "
                     "`Tuple`, `Dict`) for batching. Set `shared_memory=False` "
                     "if you use custom observation spaces."
-                )
+                ) from e
         else:
             _obs_buffer = None
             self.observations = create_empty_array(

gymnasium/vector/utils/spaces.py

@@ -180,8 +180,9 @@ def _iterate_discrete(space, items):
 def _iterate_base(space, items):
     try:
         return iter(items)
-    except TypeError:
+    except TypeError as e:
-        raise TypeError(f"Unable to iterate over the following elements: {items}")
+        raise TypeError(f"Unable to iterate over the following elements: "
+                        f"{items}") from e
 
 
 @iterate.register(Tuple)

gymnasium/wrappers/frame_stack.py

@@ -36,10 +36,10 @@ class LazyFrames:
         if lz4_compress:
             try:
                 from lz4.block import compress
-            except ImportError:
+            except ImportError as e:
                 raise DependencyNotInstalled(
                     "lz4 is not installed, run `pip install gymnasium[other]`"
-                )
+                ) from e
 
             frames = [compress(frame) for frame in frames]
         self._frames = frames

gymnasium/wrappers/human_rendering.py

@@ -89,10 +89,10 @@ class HumanRendering(gym.Wrapper):
         """Fetch the last frame from the base environment and render it to the screen."""
         try:
             import pygame
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
                 "pygame is not installed, run `pip install gymnasium[box2d]`"
-            )
+            ) from e
         if self.env.render_mode == "rgb_array_list":
             last_rgb_array = self.env.render()
             assert isinstance(last_rgb_array, list)

gymnasium/wrappers/resize_observation.py

@@ -59,10 +59,10 @@ class ResizeObservation(gym.ObservationWrapper):
         """
         try:
             import cv2
-        except ImportError:
+        except ImportError as e:
             raise DependencyNotInstalled(
-                "opencv is not install, run `pip install gymnasium[other]`"
+                "opencv is not installed, run `pip install gymnasium[other]`"
-            )
+            ) from e
 
         observation = cv2.resize(
             observation, self.shape[::-1], interpolation=cv2.INTER_AREA