[Crash] Crash in instrumented tests: java.lang.RuntimeException: Failed to call observer method

[sv-ohorvath]

Steps to reproduce

Failing UI test: org.mozilla.fenix.ui.NavigationToolbarTest#goBackTest

Test report: https://console.firebase.google.com/u/0/project/moz-fenix/testlab/histories/bh.66b7091e15d53d45/matrices/8229397304259493389/executions/bs.419e48010fba6b1a

Test report logcat

StackTrace:
java.lang.RuntimeException: Failed to call observer method FATAL EXCEPTION: DefaultDispatcher-worker-3 Process: org.mozilla.fenix.debug, PID: 12996 java.lang.RuntimeException: Failed to call observer method at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:226) at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeMethodsForEvent(ClassesInfoCache.java:194) at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeCallbacks(ClassesInfoCache.java:185) at androidx.lifecycle.ReflectiveGenericLifecycleObserver.onStateChanged(ReflectiveGenericLifecycleObserver.java:37) at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361) at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300) at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339) at androidx.lifecycle.LifecycleRegistry.addObserver(LifecycleRegistry.java:196) at mozilla.components.lib.state.ext.StoreExtensionsKt.flow(StoreExtensions.kt:155) at mozilla.components.lib.state.ext.FragmentKt.consumeFlow(Fragment.kt:94) at mozilla.components.lib.state.ext.FragmentKt.consumeFlow$default(Fragment.kt:84) at org.mozilla.fenix.browser.BaseBrowserFragment.observeTabSource$app_debug(BaseBrowserFragment.kt:894) at org.mozilla.fenix.browser.BaseBrowserFragment$onViewCreated$1.invokeSuspend(BaseBrowserFragment.kt:235) at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33) at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56) at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:571) at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:738) at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:678) at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:665) Caused by: java.lang.IllegalThreadStateException: Must have a Handler at org.mozilla.geckoview.GeckoResult.then(GeckoResult.java:476) at org.mozilla.geckoview.GeckoResult.then(GeckoResult.java:366) at org.mozilla.geckoview.WebExtensionController.ensureBuiltIn(WebExtensionController.java:593) at mozilla.components.browser.engine.gecko.GeckoEngine.installWebExtension(GeckoEngine.kt:211) at mozilla.components.support.webextensions.WebExtensionController.install(WebExtensionController.kt:54) at mozilla.components.support.webextensions.WebExtensionController.install$default(WebExtensionController.kt:50) at mozilla.components.feature.accounts.FxaWebChannelFeature.start(FxaWebChannelFeature.kt:81) at mozilla.components.support.base.feature.ViewBoundFeatureWrapper.start$support_base_release(ViewBoundFeatureWrapper.kt:160) at mozilla.components.support.base.feature.LifecycleBinding.start(ViewBoundFeatureWrapper.kt:196) at java.lang.reflect.Method.invoke(Native Method) at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:216) ... 18 more

Expected behavior

Actual behavior

Device information

• Android device: Pixel 2, API 28, virtual device
• Fenix version: Debug 12/15

┆Issue is synchronized with this Jira Task

[csadilek]

This seems to be happening (relatively low volume) only for the FxA web extension. We should only be calling feature.start on the main thread so the gecko result should have a handler. Needs investigation.

https://sentry.prod.mozaws.net/operations/firefox-nightly/issues/10160052/

[csadilek]

This looks to be a regression of f823a5d which sets up a consumeFlow call on an IO thread. Let's fix this before it hits beta.