[BUG] Incompatibility with other plugins

[ehhc]

Your Environment

• Plugin version: 0.2.0
• Platform: Android
• OS version: Windows
• Device manufacturer / model:
• Plugin config: --> Example folder

To Reproduce
Steps to reproduce the behavior:

1. Open the example project
2. Add image_picker: 0.4.12+1 as a dependency
3. Install app
4. Close app (minimizinig is not enough)
5. Trigger a headless background fetch event => adb shell cmd jobscheduler run -f com.transistorsoft.flutter.backgroundfetch.backgroundfetchexample 999
6. See error below

Debug logs

04-10 10:56:12.838 16400 16400 D TSBackgroundFetch: - Background Fetch event received
04-10 10:56:12.850 16400 16400 D TSBackgroundFetch: - finish
04-10 10:56:12.850 16400 16400 D TSBackgroundFetch: - jobFinished
04-10 10:56:12.865 16400 16400 D TSBackgroundFetch: HeadlessJobService onStartJob
04-10 10:56:12.866 16400 16400 D TSBackgroundFetch: 💀 [HeadlessTask]
04-10 10:56:13.247 16400 16400 E JobServiceEngine: Error while executing job: 998
04-10 10:56:13.248 16400 16400 D AndroidRuntime: Shutting down VM
04-10 10:56:13.257 16400 16400 E AndroidRuntime: FATAL EXCEPTION: main
04-10 10:56:13.257 16400 16400 E AndroidRuntime: Process: com.transistorsoft.flutter.backgroundfetch.backgroundfetchexample, PID: 16400
04-10 10:56:13.257 16400 16400 E AndroidRuntime: java.lang.RuntimeException: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File android.app.Activity.getExternalFilesDir(java.lang.String)' on a null object reference
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at android.app.job.JobServiceEngine$JobHandler.handleMessage(JobServiceEngine.java:112)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at android.os.Handler.dispatchMessage(Handler.java:106)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at android.os.Looper.loop(Looper.java:164)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at android.app.ActivityThread.main(ActivityThread.java:6494)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at java.lang.reflect.Method.invoke(Native Method)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
04-10 10:56:13.257 16400 16400 E AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File android.app.Activity.getExternalFilesDir(java.lang.String)' on a null object reference
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at io.flutter.plugins.imagepicker.ImagePickerPlugin.registerWith(ImagePickerPlugin.java:27)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at io.flutter.plugins.GeneratedPluginRegistrant.registerWith(GeneratedPluginRegistrant.java:17)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at com.transistorsoft.flutter.backgroundfetch.backgroundfetchexample.Application.registerWith(Application.java:17)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at com.transistorsoft.flutter.backgroundfetch.HeadlessTask.initFlutterView(HeadlessTask.java:133)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at com.transistorsoft.flutter.backgroundfetch.HeadlessTask.<init>(HeadlessTask.java:47)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at com.transistorsoft.flutter.backgroundfetch.HeadlessJobService.onStartJob(HeadlessJobService.java:38)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at android.app.job.JobService$1.onStartJob(JobService.java:71)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        at android.app.job.JobServiceEngine$JobHandler.handleMessage(JobServiceEngine.java:108)
04-10 10:56:13.257 16400 16400 E AndroidRuntime:        ... 6 more
04-10 10:56:13.273   767   782 I ActivityManager: Showing crash dialog for package com.transistorsoft.flutter.backgroundfetch.backgroundfetchexample u0
04-10 10:56:13.281   767   781 W BroadcastQueue: Background execution not allowed: receiving Intent { act=android.intent.action.DROPBOX_ENTRY_ADDED flg=0x10 (has extras) } to com.google.android.gms/.stats.service.DropBoxEntryAddedReceiver
04-10 10:56:13.281   767   781 W BroadcastQueue: Background execution not allowed: receiving Intent { act=android.intent.action.DROPBOX_ENTRY_ADDED flg=0x10 (has extras) } to com.google.android.gms/.chimera.GmsIntentOperationService$PersistentTrustedReceiver

Do you have any ideas how to fix this? :)

[christocracy]

It's due to a bug in image_picker, which they fixed in 0.5.0+3. Upgrade to latest image_picker.

[ehhc]

oh, .. thanks for the quick response

[christocracy]

When your app boots Headless, many plugins make the mistake of naively referencing registrar.activity(). There is no Activity in Headless Mode.

Plugins need to first check if (registrar.activity() != null) { }, which is what image_picker did in their v0.5.0+3

[ehhc]

The location plugin has the same problem -.-

btw: is there anyway to un-register a headless task? Since i don't have to start the background_fetch for headless tasks, i assume, i cannot stop it by calling BackgroundFetch.stop()??

[christocracy]

The location plugin has the same problem -.-

What location plugin? Why don't you use my flutter_background_geolocation?

is there anyway to un-register a headless task?

Why would you do that? Just call #stop.

[ehhc]

this plugin: https://github.com/Lyokone/flutterlocation
I need it to access the location while the app is in the foreground.
But thanks to your hint above i was able to fix the issue and create a PR (see the referenced issue above) thanks therefore.

Anyway: I still plan to use your background_geolocation plugin as well. For location tracking. Unfortunately, the app I'm developing is part of a research project for my university. Therefore, I'll not be able to buy your plugin because it's only a prototype, we're developing :(

is there anyway to un-register a headless task?

Why would you do that? Just call #stop.

You're right: that question was stupid.

Thanks a lot for your quick and good help :)

[christocracy]

Anyway: I still plan to use your background_geolocation plugin as well.

This is what you pay for: full time support. This plugin is not a side-project, I've supported it full time for > 4 years (it was originally developed for Cordova and React Native).

[ehhc]

if i would be able to buy it, i would like to. But as i said, it's just a research prototype, so that's a bit difficult.. :(
Nonetheless, i will try to figure out if there is a way to buy a licence of your plugin, even though i fear that's unlikely :(