Don't crash on Shake errors

During the initial full generation we are not handing exceptions from
Shake (which can happen due to parser errors from user code). This
change handles it.

src/Rib/App.hs

@@ -90,7 +90,6 @@ runWith src dst buildAction = \case
     putStrLn $ "[Rib] Watching " <> toFilePath src <> " for changes"
     void $ watchTree mgr (toFilePath src) (const True) $ \_ -> do
       runShake False
-        `catch` \(e :: SomeException) -> putStrLn $ show e
     -- Wait forever, effectively.
     forever $ threadDelay maxBound
   Serve p dw ->
@@ -101,10 +100,14 @@ runWith src dst buildAction = \case
     runShake fullGen
   where
     runShake fullGen =
-      flip shakeForward buildAction $
-        shakeOptions
-          { shakeVerbosity = Verbose,
-            shakeRebuild = bool [] [(RebuildNow, "**")] fullGen,
-            shakeLintInside = [""],
-            shakeExtra = addShakeExtra (RibSettings src dst) (shakeExtra shakeOptions)
-          }
+      shakeForward (ribShakeOptions fullGen) buildAction
+        -- Gracefully handle any exceptions when running Shake actions. We want
+        -- Rib to keep running instead of crashing abruptly.
+        `catch` \(e :: SomeException) -> putStrLn $ "[Rib] Shake error: " <> show e
+    ribShakeOptions fullGen =
+      shakeOptions
+        { shakeVerbosity = Verbose,
+          shakeRebuild = bool [] [(RebuildNow, "**")] fullGen,
+          shakeLintInside = [""],
+          shakeExtra = addShakeExtra (RibSettings src dst) (shakeExtra shakeOptions)
+        }