[bug]: Service throws an exception with some apps

[DaveTryon]

Describe the bug

Some apps, like Flipgrid in camera view, throw an exception inside axe-android. We've reported this exception to deque at dequelabs/axe-android#127, but we can also add a workaround on our side until the bug is fixed.

To Reproduce
Steps to reproduce the behavior:

1. Launch FlipGrid on your device.
2. Start Accessibility Insights for Android
3. Scan FlipGrid--it completes successfully
4. Tap the camera icon on FlipGrid
5. Press the "Start Over" button in Accessibility Insights for Android

Actual behavior:

You get a "device disconnected" message

Expected behavior

You should get a scan of the camera page, including issues (there are several touch size violations, for example)

Context (please complete the following information)

• Android Version: 10
• Service Version & Environment: 2020.1124.4
• Target Application: Flipgrid 9.2.0

Here's the actual exception being thrown:

An Exception was thrown!
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.hashCode()' on a null object reference at
com.deque.axe.android.AxePropCalculator.getCalculatedProps(AxePropCalculator.java:56) at
com.deque.axe.android.AxeView.calculateProps(AxeView.java:429) at
com.deque.axe.android.AxeView.(AxeView.java:194) at
com.deque.axe.android.AxeView.(AxeView.java:208) at
com.deque.axe.android.AxeView$Builder.build(AxeView.java:156) at
com.microsoft.accessibilityinsightsforandroidservice.AxeViewsFactory.buildAxeViews(AxeViewsFactory.java:69) at
com.microsoft.accessibilityinsightsforandroidservice.AxeViewsFactory.buildAxeViewsWithRetries(AxeViewsFactory.java:41) at
com.microsoft.accessibilityinsightsforandroidservice.AxeViewsFactory.createAxeViews(AxeViewsFactory.java:32) at
com.microsoft.accessibilityinsightsforandroidservice.AxeContextFactory.createAxeContext(AxeContextFactory.java:30) at
com.microsoft.accessibilityinsightsforandroidservice.AxeScanner.scanWithAxe(AxeScanner.java:24) at
com.microsoft.accessibilityinsightsforandroidservice.ResultRequestFulfiller.getScanContent(ResultRequestFulfiller.java:68) at
com.microsoft.accessibilityinsightsforandroidservice.ResultRequestFulfiller.lambda$fulfillRequest$0$ResultRequestFulfiller(ResultRequestFulfiller.java:39) at
com.microsoft.accessibilityinsightsforandroidservice.-$$Lambda$ResultRequestFulfiller$yG6us3t3DTAXfswnmqRdFfQBoSE.accept(Unknown Source:6) at
com.microsoft.accessibilityinsightsforandroidservice.ScreenshotController.lambda$getImageReader$0$ScreenshotController(ScreenshotController.java:78) at
com.microsoft.accessibilityinsightsforandroidservice.-$$Lambda$ScreenshotController$7og7qnDPiWyGIKAMcU5BF-Q6rTk.accept(Unknown Source:6) at
com.microsoft.accessibilityinsightsforandroidservice.OnScreenshotAvailable.onImageAvailable(OnScreenshotAvailable.java:51) at
android.media.ImageReader$ListenerHandler.handleMessage(ImageReader.java:798) at
android.os.Handler.dispatchMessage(Handler.java:107) at
android.os.Looper.loop(Looper.java:237) at
android.os.HandlerThread.run(HandlerThread.java:67)

Are you willing to submit a PR?

Yes

Did you search for similar existing issues?

Yes--this has the same symptom as #61 (closed for lack of response from the filer), but it may or may not be the same root cause.

Additional context

[ghost]

This issue has been marked as ready for team triage; we will triage it in our weekly review and update the issue. Thank you for contributing to Accessibility Insights!

[DaveTryon]

@juchampa, this can only be closed after we release an updated version of the service and consume that service in the unified client. It could probably be deferred until we complete the service-side feature around focus tracking

[DaveTryon]

This is now in canary builds, so closing the issue