Chromecast JS: Improve error logging.

[Codex-]

I was investigating an issue I was having with casting (which has been fixed somewhere between the Playstore release and the tip of master) and found whenever the Chromecast js logged an error it was not stringified and thus would log [object Object].

EDIT: Actually my issue is still present when using the gradle options to build, will raise an issue.

This PR addresses this by attempting to stringify the instance of chrome.cast.Error, if this fails or throws then the original behaviour will be used.

Before:

2021-03-21 01:25:37.543 7245-7245/org.jellyfin.mobile.debug I/chromium: [INFO:CONSOLE(1444)] "Encountered cast error [object Object]", source: https://www.gstatic.com/cv/js/sender/v1/cast_sender.js (1444)

After:

2021-03-21 00:42:35.321 28384-28384/org.jellyfin.mobile.debug I/chromium: [INFO:CONSOLE(1434)] "Encountered cast error {"code":"unknown","description":"status{statuscode=success, resolution=null} undefined","details":{}}", source: https://www.gstatic.com/cv/js/sender/v1/cast_sender.js (1434)

[nielsvanvelzen]

I'm quite sure the actual objects shows up when you use the chromium developer tools (in a chromium based browser go to chrome://inspect and the webview should show up with an "inspect" link).

[Maxr1998]

They should, yes. Not sure what would be preferable here, better support for devtools (for developers) or more transparency when reading logs (for users).

[nielsvanvelzen]

Most users will post their logs from retrieved from adb in issues so I think it makes sense to improve those messages.

[Codex-]

Rebased.