HTML-ized Tahoe-LAFS WAPI errors are unwieldy

[crwood]

By default, the Tahoe-LAFS web API wraps response bodies for HTTP 500 errors in HTML/CSS, making it more difficult for applications like Gridsync to parse and/or display such content to humans in text form. As it turns out, there's a way to disable this behavior and have such stack traces returned in plain text. From the Tahoe-LAFS WAPI docs:

Unusual exceptions may result in a 500 Internal Server Error as a catch-all, with a default response body containing a Nevow-generated HTML-ized representation of the Python exception stack trace that caused the problem. CLI programs which want to copy the response body to stderr should provide an “Accept: text/plain” header to their requests to get a plain text stack trace instead.

Gridsync's interactions with the Tahoe-LAFS web API should include this header where possible in order to facilitating the handling of such errors.

See also tahoe-lafs/magic-folder#679