iOS Simulator hangs when code error

Hi, I am new to React native and also Expo … that said, I make a fair number of code mistakes.
When I do so, sometimes the iOS simulator just seems to hang during the reloading process; it does not give me a red screen or a yellow warning. Removing the offending code causes it to reload correctly.

My question is, how can I see what is going on? I am not clear what the code mistake is since I cannot get the feedback, and I resort to deleting code then googling how to do what I want.

Hi, is there anything in your packager log? (e.g. “unhandled promise rejection” or something like that?) Do you have dev mode enabled?

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Thanks Ben – I do have dev mode enabled. I just got my Android emulator working and now there is a warning in the android emulator about a missing required property on Button … but the IOS simulator is still hanging on reload.

I also do NOW see the message in the packager log but I did not before.

So … when I am only running the iOS simulator I do not see the message in the log and the simulator reload hangs. When I am running both the Android emulator and iOS simulator I do see the message in the log and the Android reloads with the warning.

All I am doing to reproduce this is to add a JSX tag in the middle of my view, without importing Button.

One more thing: if I press command-I in expo to re-launch the app in the iOS simulator, I DO see the warning, so this this apparently isolated to the auto-refresh code.