Rewrote service trait join() method to allow thread join handles to return values other than ()

src/broadcast_stage.rs

@@ -217,6 +217,7 @@ impl Service for BroadcastStage {
     type JoinReturnType = ();
 
     fn join(self) -> thread::Result<()> {
-        self.thread_hdl.join()
+        self.thread_hdl.join()?;
+        Ok(())
     }
 }

src/record_stage.rs

@@ -146,7 +146,8 @@ impl Service for RecordStage {
     type JoinReturnType = ();
 
     fn join(self) -> thread::Result<()> {
-        self.thread_hdl.join()
+        self.thread_hdl.join()?;
+        Ok(())
     }
 }
 

src/request_stage.rs

@@ -117,6 +117,7 @@ impl Service for RequestStage {
     type JoinReturnType = ();
 
     fn join(self) -> thread::Result<()> {
-        self.thread_hdl.join()
+        self.thread_hdl.join()?;
+        Ok(())
     }
 }

src/rpc.rs

@@ -71,7 +71,8 @@ impl Service for JsonRpcService {
     type JoinReturnType = ();
 
     fn join(self) -> thread::Result<()> {
-        self.thread_hdl.join()
+        self.thread_hdl.join()?;
+        Ok(())
     }
 }