[Android] [Crash] Check if fresco is initialised before clearing memory caches

[AndrewJack]

Motivation

Fixes the following crash:

Fatal Exception: java.lang.RuntimeException: Unable to destroy activity {com.example/com.example.MainActivity}: java.lang.NullPointerException: ImagePipelineFactory was not initialized!
       at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3831)
       at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3849)
       at android.app.ActivityThread.access$1500(ActivityThread.java:150)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1398)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:148)
       at android.app.ActivityThread.main(ActivityThread.java:5417)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:764)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
Caused by java.lang.NullPointerException: ImagePipelineFactory was not initialized!
       at com.facebook.common.internal.Preconditions.checkNotNull(Preconditions.java:226)
       at com.facebook.imagepipeline.core.ImagePipelineFactory.getInstance(ImagePipelineFactory.java:74)
       at com.facebook.drawee.backends.pipeline.Fresco.getImagePipelineFactory(Fresco.java:92)
       at com.facebook.drawee.backends.pipeline.Fresco.getImagePipeline(Fresco.java:97)
       at com.facebook.react.modules.fresco.FrescoModule.onHostDestroy(FrescoModule.java:186)
       at com.facebook.react.bridge.ReactContext.onHostDestroy(ReactContext.java:240)
       at com.facebook.react.ReactInstanceManager.moveToBeforeCreateLifecycleState(ReactInstanceManager.java:667)
       at com.facebook.react.ReactInstanceManager.onHostDestroy(ReactInstanceManager.java:586)
       at com.facebook.react.ReactInstanceManager.onHostDestroy(ReactInstanceManager.java:599)
       at com.facebook.react.ReactActivityDelegate.onDestroy(ReactActivityDelegate.java:142)
       at com.facebook.react.ReactActivity.onDestroy(ReactActivity.java:72)
       at android.app.Activity.performDestroy(Activity.java:6456)
       at android.app.Instrumentation.callActivityOnDestroy(Instrumentation.java:1143)
       at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3818)
       at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3849)
       at android.app.ActivityThread.access$1500(ActivityThread.java:150)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1398)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:148)
       at android.app.ActivityThread.main(ActivityThread.java:5417)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:764)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)

This was introduced by d9ae27b

Test Plan

1. Create app with an image to be loaded
2. Background app before fresco has been initialised. (Very tight window to do this)
3. Should not crash

cc @foghina

[yaxin3690]

Yes, I also have this problem

[ianlin]

This happens sometimes on some of our production devices as well.

[AndrewJack]

@hramos Is there anyone who can review/merge this?

[pull-bot]

This PR has been submitted by a core contributor.

Generated by 🚫 dangerJS

[piotrek1543]

Good work!

[facebook-github-bot]

I tried to merge this pull request into the Facebook internal repo but some checks failed. To unblock yourself please check the following: Does this pull request pass all open source tests on GitHub? If not please fix those. Does the code still apply cleanly on top of GitHub master? If not can please rebase. In all other cases this means some internal test failed, for example a part of a fb app won't work with this pull request. I've added the Import Failed label to this pull request so it is easy for someone at fb to find the pull request and check what failed. If you don't see anyone comment in a few days feel free to comment mentioning one of the core contributors to the project so they get a notification.