Improve error handling in preparation of gopass 1.10

[Pharb]

RELEASE_NOTES=Improve error handling for gopass 1.10 upgrade

Handle:

• Native host has exited
• Error when communicating with the native messaging host
• An unexpected error occurred (=> strange Firefox behaviour, probably broken in the browser?)
• Native application tried to send a message...

[codecov]

Codecov Report

Merging #166 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #166   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            9         9           
  Lines          717       717           
  Branches       120       120           
=========================================
  Hits           717       717           

Impacted Files	Coverage Δ
web-extension/popup.js	100.00% <ø> (ø)

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[Pharb]

Part of #165

[Pharb]

Checked again with latest gopasspw/gopass@1ff797e master.

[lockejan]

RELEASE_NOTES=Improve error handling for gopass 1.10 upgrade

Handle:

• Native host has exited
• Error when communicating with the native messaging host
• An unexpected error occurred (=> strange Firefox behaviour, probably broken in the browser?)
• Native application tried to send a message...

Hey, how can I debug such errors? I'm currently facing "Native host has exited" and "Error when communicating with the native messaging host."

Dev-Tools are giving me:

DevTools failed to load source map: Could not load content for chrome-extension://kkhfnlkhiapbiehimabddjbimfaijdhk/vendor/browser-polyfill.js.map: HTTP error: status code 404, net::ERR_UNKNOWN_URL_SCHEME"