Give more informative messages about invariant violations

hyperthunk · hyperthunk · commit 9cdaebcfb19b · 2018-11-10T21:20:15.000Z
diff --git a/src/Control/Distributed/Process/Internal/Primitives.hs b/src/Control/Distributed/Process/Internal/Primitives.hs
@@ -403,7 +403,8 @@ receiveWait ms = do
   mProc <- liftIO $ dequeue queue Blocking (map unMatch ms)
   case mProc of
     Just proc' -> proc'
-    Nothing    -> error "Well... That wasn't supposed to happen! o_O"
+    Nothing    -> die $ "System Invariant Violation: CQueue.hs returned `Nothing` "
+                     ++ "in the absence of a timeout value."
 
 -- | Like 'receiveWait' but with a timeout.
 --
diff --git a/src/Control/Distributed/Process/Management/Internal/Trace/Primitives.hs b/src/Control/Distributed/Process/Management/Internal/Trace/Primitives.hs
@@ -174,5 +174,6 @@ withRegisteredTracer act = do
                    --     is not considered cool in later versions of MonadFail
                    case mTP of
                      Just p' -> act p'
-                     Nothing -> die "Initial Tracer Name Not Registered"
+                     Nothing -> die $ "System Invariant Violation: Initial Tracer "
+                                   ++ "Name Not Found (whereis tracer.initial)"
     (Just p) -> act p
