While trying to reproduce bug 68472 I triggered network errors:

1. View a Flow board on local MW server.
2. Open browser
3. On server rename api.php to api_BROKEN.php
4. Click Summrize topic, or click Reply and then click [Reply], etc.

Result: nothing is reported to the user despite the api response being 404 Not Found. The console reports a JS error

TypeError: result.error is undefined

from
if ( result.error.prev_revision ) in apiHandlers[ handlerName ] fail().

In this failure case, there's no result.error , hence the JS error. Even if avoided, Flow displays "undefioned" in its pink errorbox because there's nothing in result.error.info; it seems that if there's a network error the failure information is in result.exception ("Not found") and result.textStatus ("error"). (It sucks that different levels of API failure put information in different pieces of the result object.)

Version: master
Severity: minor