Working in "Reading Mode" in Firefox and other browsers

[inputsh]

Okay, this is a bit weird, but when viewing an article in Firefox's Reading Mode, I always get the internal server error:

Failed to save page https://domain.tld/api/entries.json
{"error":{"code":500,"message":"Internal Server Error"}}

Exiting the reading mode and clicking on the icon again saves the link just fine, but the reading mode always activates the 500 error. This seems a bit weird to me, since I assumed that wallabagger copies the URL from the address bar, but the address bar doesn't get changed at all while being in the reading mode. Guess I was wrong.

Both the Wallabag installation and Firefox extension have been set up less than 24 hours ago, so I'm assuming I'm running the latest stable versions of both.

[Rurik19]

Wallabagger gets url from tab object, not from address bar. In case of reading mode in FF, that url is:
about:reader?url=https%3A%2F%2Fgeektimes.ru%2Fpost%2F288150%2F
All urls that begins with "about:", "browser:", "chrome:" wallabagger filters as service and do nothing. So, I think we should treat "about:reader" separately. And others browsers like Yandex or Vivaldi have its own "reader mode". So, I rename this issue and close #74 as it have same topic (in general)

[ghost]

Firefox has the tab.isInReaderMode property to detect reader view but understandably they are the only browser to support it. So reader view is probably best detected by checking that the URL scheme and pathname are about:reader.

There does not seem to be a good way of adding an icon to the reader view sidebar as in #74. Pocket is able to do it by virtue of being embeded inside Firefox (see SaveToPocket.jsm#L326).

[andrewshadura]

This would probably autosolved if #248 were implemented.