improve "not a registered callable module" error message

[vonovak]

Summary

Motivation:

Invariant Violation: Module AppRegistry is not a registered callable module (calling runApplication). is an error that happens rarely, and most SO answers end up recommending to use react-native bundle to work around. I stumbled upon this error the other day and it took me a while to figure out that the error was caused by the fact that my entryFile path was pointing to an existing but invalid file. I figured it would be nice to mention this because I believe this will be a frequent cause of the error.

Changelog

[General] [Changed] - improve "not a registered callable module error message"

Test Plan

tested locally with RNTester, prints

[Sun May 17 2020 18:15:55.396]  ERROR    Invariant Violation: Module AppRegistry is not a registered callable module (calling runApplication). This can happen when the application entry file path is incorrect.
      On Android, verify 'getJSMainModuleName()' in 'MainApplication.java' and 'project.ext.react.entryFile' in 'android/app/build.gradle'.
      On iOS, verify '- (NSURL *)sourceURLForBridge:(RCTBridge *)bridge' in 'AppDelegate.m' and 'ENTRY_FILE' env. variable passed to 'react-native-xcode.sh' (if any) in 'Build Phases' -> 'Bundle React Native code and images'.

in metro logs

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
ios	-	universal	n/a	--

Base commit: 46d6e7f

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	6,782,171	21,003
android	hermes	armeabi-v7a	6,446,338	22,212
android	hermes	x86	7,169,249	20,435
android	hermes	x86_64	7,060,562	21,835
android	jsc	arm64-v8a	8,949,937	17,086
android	jsc	armeabi-v7a	8,606,518	18,340
android	jsc	x86	8,780,138	16,529
android	jsc	x86_64	9,357,098	17,952

Base commit: 46d6e7f

[vonovak]

hello, @fkgozali I heard you might be the right person to review, would you mind taking a look at this? Thank you in advance! :)

[fkgozali]

The error message for Android/iOS here assumes specific usage of a build system, which is not always the case (e.g. some uses BUCK to build). I'd just remove them, or provide url to a section in the https://reactnative.dev/ with platform specific instructions.

This can happen when the application entry file path is incorrect.

Note that this is not the only reasons this error happens, some times a bad JS bundle, or an early initialization error when loading React Native will cause this error.

[vonovak]

@fkgozali I updated the message, please let me know if this is ok or not. Thanks

[vonovak]

@fkgozali hello again, would you please share your thoughts on this? Thanks!

[fkgozali]

Sorry for the delay, I'm merging this.

[facebook-github-bot]

@fkgozali has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[react-native-bot]

This pull request was successfully merged by @vonovak in e27d656.

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