fix(error handling): Simplified error handling

packages/learn/src/templates/Challenges/redux/completion-epic.js

@@ -1,5 +1,4 @@
 import { of } from 'rxjs/observable/of';
-import { _if } from 'rxjs/observable/if';
 import { empty } from 'rxjs/observable/empty';
 import {
   switchMap,
@@ -29,8 +28,7 @@ import {
   openDonationModal,
   shouldShowDonationSelector,
   updateComplete,
-  updateFailed,
-  isOnlineSelector
+  updateFailed
 } from '../../../redux/app';
 
 import postUpdate$ from '../utils/postUpdate$';
@@ -49,13 +47,7 @@ function postChallenge(update, username) {
         updateComplete()
       )
     ),
-    catchError(({ _body, _endpoint }) => {
-      let payload = _body;
-      if (typeof _body === 'string') {
-        payload = JSON.parse(_body);
-      }
-      return of(updateFailed({ endpoint: _endpoint, payload }));
-    })
+    catchError(() => of(updateFailed(update)))
   );
   return saveChallenge;
 }
@@ -79,11 +71,7 @@ function submitModern(type, state) {
         endpoint: '/external/modern-challenge-completed',
         payload: challengeInfo
       };
-      return _if(
-        () => isOnlineSelector(state),
-        postChallenge(update, username),
-        of(updateFailed(update))
-      );
+      return postChallenge(update, username);
     }
   }
   return empty();
@@ -106,12 +94,8 @@ function submitProject(type, state) {
     endpoint: '/external/project-completed',
     payload: challengeInfo
   };
-  return _if(
-    () => isOnlineSelector(state),
-    postChallenge(update, username).pipe(
-      concat(of(updateProjectFormValues({})))
-    ),
-    of(updateFailed(update))
+  return postChallenge(update, username).pipe(
+    concat(of(updateProjectFormValues({})))
   );
 }
 
@@ -130,11 +114,7 @@ function submitBackendChallenge(type, state) {
         endpoint: '/external/backend-challenge-completed',
         payload: challengeInfo
       };
-      return _if(
-        () => isOnlineSelector(state),
-        postChallenge(update, username),
-        of(updateFailed(update))
-      );
+      return postChallenge(update, username);
     }
   }
   return empty();

packages/learn/src/templates/Challenges/redux/current-challenge-epic.js

@@ -1,4 +1,3 @@
-import { _if } from 'rxjs/observable/if';
 import { of } from 'rxjs/observable/of';
 import { ofType } from 'redux-observable';
 
@@ -8,8 +7,7 @@ import {
   isSignedInSelector,
   currentChallengeIdSelector,
   updateComplete,
-  updateFailed,
-  isOnlineSelector
+  updateFailed
 } from '../../../redux/app';
 import postUpdate$ from '../utils/postUpdate$';
 
@@ -25,18 +23,10 @@ function currentChallengeEpic(action$, { getState }) {
           currentChallengeId: payload
         }
       };
-      return _if(
-        () => isOnlineSelector(getState()),
-        postUpdate$(update).pipe(mapTo(updateComplete())),
-        of(updateFailed(update))
-      );
-    }),
-    catchError(({ _body, _endpoint }) => {
-      let payload = _body;
-      if (typeof _body === 'string') {
-        payload = JSON.parse(_body);
-      }
-      return of(updateFailed({ endpoint: _endpoint, payload }));
+      return postUpdate$(update).pipe(
+          mapTo(updateComplete()),
+          catchError(() => of(updateFailed(update)))
+        );
     })
   );
 }

packages/learn/src/templates/Challenges/utils/ajax-stream.js

@@ -20,6 +20,8 @@ import debugFactory from 'debug';
 import { Observable, noop } from 'rxjs';
 import { map } from 'rxjs/operators';
 
+import { isGoodXHRStatus } from './';
+
 const debug = debugFactory('fcc:ajax$');
 const root = typeof window !== 'undefined' ? window : {};
 
@@ -67,14 +69,19 @@ function getCORSRequest() {
 
 function parseXhrResponse(responseType, xhr) {
   switch (responseType) {
-    case 'json':
-      if ('response' in xhr) {
-        return xhr.responseType
-          ? xhr.response
-          : JSON.parse(xhr.response || xhr.responseText || 'null');
+    case 'json': {
+      if (isGoodXHRStatus(xhr.status)) {
+        if ('response' in xhr) {
+          return xhr.responseType
+            ? xhr.response
+            : JSON.parse(xhr.response || xhr.responseText || 'null');
+        } else {
+          return JSON.parse(xhr.responseText || 'null');
+        }
       } else {
-        return JSON.parse(xhr.responseText || 'null');
+        return null;
       }
+    }
     case 'xml':
       return xhr.responseXML;
     case 'text':
@@ -293,7 +300,7 @@ export function postJSON$(url, body) {
       Accept: 'application/json'
     },
     normalizeError: (e, xhr) => parseXhrResponse('json', xhr)
-  }).pipe(map(({ response }) => response));
+  });
 }
 
 // Creates an observable sequence from an Ajax GET Request with the body.
@@ -318,5 +325,5 @@ export function getJSON$(url) {
       Accept: 'application/json'
     },
     normalizeError: (e, xhr) => parseXhrResponse('json', xhr)
-  }).map(({ response }) => response);
+  }).pipe(map(({ response }) => response));
 }

packages/learn/src/templates/Challenges/utils/index.js

@@ -3,3 +3,8 @@ const guideBase = 'https://guide.freecodecamp.org/certifications';
 export function createGuideUrl(slug = '') {
   return guideBase + slug;
 }
+
+export function isGoodXHRStatus(status) {
+  const statusInt = parseInt(status, 10);
+  return statusInt >= 200 && statusInt < 400;
+}