bug + fix: Push Notification handlers not called after webViewWebContentProcessDidTerminate

[hermitdemschoenenleben]

Bug Report

In our ios app we found that a click on a push message sometimes doesn't execute the javascript push message handlers. We found out that this happens after the webview process has been shut down in background (see also https://github.com/ionic-team/capacitor/discussions/5488 and https://github.com/ionic-team/capacitor/issues/2379) which may happen due to memory pressure. This shutdown calls webViewWebContentProcessDidTerminate which reloads the app. After this reload, push notification handlers aren't executed. This issue can be reproduced reliably (see code reproduction below).

Update: I now think this problem isn't specific to the push notifications plugin. I think it's a general problem caused by not clearing plugins' event listeners after reloading the webview. See my comment for a suggested fix.

Capacitor Version

💊   Capacitor Doctor  💊

Latest Dependencies:

  @capacitor/cli: 5.0.5
  @capacitor/core: 5.0.5
  @capacitor/android: 5.0.5
  @capacitor/ios: 5.0.5

Installed Dependencies:

  @capacitor/android: not installed
  @capacitor/cli: 5.0.5
  @capacitor/core: 5.0.5
  @capacitor/ios: 5.0.5

[success] iOS looking great! 👌

Platform(s)

ios

Current Behavior

After webViewWebContentProcessDidTerminate, a tap on a push message just opens the app but doesn't call pushNotificationActionPerformed.

Expected Behavior

After app-reload following webViewWebContentProcessDidTerminate, push messages that were delivered to the native layer in the meantime should be replayed such that the web app may handle them.

Code Reproduction

• Clone https://github.com/hermitdemschoenenleben/pushmsgtester
• Run it in iPhone simulator
• Go the ios homescreen in order to view incoming push messages
• Drag and drop the file test-push-message.apns to the simulator to simulate a push message
• Click on the notification -> the app opens and an alert shows: push message click was recognized by the app
• Now, go to the ios homescreen again
• On your mac, execute kill $(pgrep -P $(pgrep launchd_sim) 'com.apple.WebKit.WebContent') to kill the webview process (taken from https://stackoverflow.com/a/73609765/5895643 ). This simulates what happens under memory pressure.
• Drag and drop test-push-message.apns to the simulator again
• Click on the notification -> the app opens. This time, no alert is shown, though, as the push message handler is not called after a webview crash

Additional Context

• https://github.com/ionic-team/capacitor/discussions/5488
• https://github.com/ionic-team/capacitor/issues/2379
• https://github.com/ionic-team/capacitor/issues/6153