React Native Android - Build Successful - But Doesn't Open - react-native

Question

My app builds successfully, opens on the emulator, then immediately shuts down. I spent almost 24 hours straight studying what could be wrong and going over all the answers and none of them work for me. Here is the final details...
BUILD SUCCESSFUL in 21s
262 actionable tasks: 1 executed, 261 up-to-date
info Running adb -s emulator-5554 reverse tcp:8081 tcp:8081
info Starting the app on emulator-5554 (adb -s emulator-5554 shell am start -n com.myapp/com.myapp.MainActivity)...
Starting: Intent { cmp=com.myapp/.MainActivity }
Would greatly appreciate someone figuring this out with me!
Here is the logcat...
10-17 13:27:27.409 3405 3492 I MicroDetector: Keeping mic open: false
10-17 13:27:27.409 3405 3492 I MicroDetectionWorker: #onError(false)
10-17 13:27:27.498 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: a: input svInfo.flags is 8
10-17 13:27:27.498 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: b: input svInfo.flags is 8
10-17 13:27:28.501 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: a: input svInfo.flags is 8
10-17 13:27:28.501 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: b: input svInfo.flags is 8
10-17 13:27:28.519 2021 2368 W AppOps : Noting op not finished: uid 10101 pkg com.google.android.gms code 41 time=1571344043502 duration=0
10-17 13:27:29.506 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: a: input svInfo.flags is 8
10-17 13:27:29.506 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: b: input svInfo.flags is 8
10-17 13:27:30.511 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: a: input svInfo.flags is 8
10-17 13:27:30.511 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: b: input svInfo.flags is 8
10-17 13:27:31.515 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: a: input svInfo.flags is 8
10-17 13:27:31.515 1756 2440 E GnssHAL_GnssInterface: gnssSvStatusCb: b: input svInfo.flags is 8
10-17 13:27:32.413 3405 3492 I MicroDetectionWorker: #startMicroDetector [speakerMode: 0]
10-17 13:27:32.414 3405 3492 W ErrorReporter: reportError [type: 211, code: 393244, bug: 0]: errorCode: 393244, engine: 0

Answer 1

try turning debugger off and on again
try building the code in xcode/android studio, inspect errors if any
usually it's a debugger issue for me. good luck!

Answer 2

Okay - I found the problem and have finally got this up and running. Way, way, way high up in the logcat was a message from Google Admob saying that I needed to add the appId in the meta tag of the AndroidManifest file. This was very hard to find because the logcat keeps running constantly and even if you look deep in the log it disappears quickly.
To figure this out I started adb logcat in a new shell (terminal window), gave it a second to fill up, then cleared it using CMD K, then in another shell ran react-native run-android.
When it fully built I immediately pressed Cmd C in the logcat window to stop it from running. Then I scrolled all the way to the top and found the error message from Google AdMob with instructions to add the following code to the AndroidManifest.xml file within the <application></application> section...
<meta-data
android:name="com.google.android.gms.ads.APPLICATION_ID"
android:value="ca-app-pub-xxxxxxxxxxxxxxxx~yyyyyyyyyy"/>
It also stated that without this the app would crash. So I added my id and now have a running app in the emulator.