Clearer HMR error messages

Summary:
GraphNotFoundError: When the user moves the app to the background on Android, restarts the Metro server and reopens the app, since the client hasn't requested either a delta or a bundle, the graph cache of the server is empty and thus we can't compute an update for the client (what if changes happened when the metro server was down?).

RevisionNotFoundError: I didn't manage to reproduce that one. It could happen if two clients live side-by-side, requesting the exact same bundle. In the future, if we want to handle that case, we'll need to manage a list of clients listening to a single graph so that we don't try to update the same graph multiple times for a single file change.

Disconnection: Same as GraphNotFoundError, but happens when the user moves the app to the background on iOS.

Reviewed By: mjesun

Differential Revision: D12960939

fbshipit-source-id: 5ac1dc7fd12bad5e0ee8dfa5a21c112773454ee5

Libraries/Utilities/HMRClient.js

@@ -89,7 +89,27 @@ Error: ${e.message}`;
 
     hmrClient.on('error', data => {
       HMRLoadingView.hide();
-      throw new Error(`${data.type} ${data.message}`);
+
+      if (data.type === 'GraphNotFoundError') {
+        hmrClient.disable();
+        throw new Error(
+          'The packager server has restarted since the last Hot update. Hot Reloading will be disabled until you reload the application.',
+        );
+      } else if (data.type === 'RevisionNotFoundError') {
+        hmrClient.disable();
+        throw new Error(
+          'The packager server and the client are out of sync. Hot Reloading will be disabled until you reload the application.',
+        );
+      } else {
+        throw new Error(`${data.type} ${data.message}`);
+      }
+    });
+
+    hmrClient.on('close', data => {
+      HMRLoadingView.hide();
+      throw new Error(
+        'Disconnected from the packager server. Hot Reloading will be disabled until you reload the application.',
+      );
     });
 
     hmrClient.enable();