Taking a look at errors in the mobile web editing experience a large chunk of errors have occurred since anonymous editing was switched on.
Since anonymous editing turned on [1]
http 57477
ve-load-error 281
ve-save-error 636
Most of these errors occur when the user is anon [2]:
http 51484
ve-load-error 141
ve-save-error 484
[1] select event_errorText, count(*) from MobileWebEditing_8599025 where event_action = 'error' and timestamp > 20150401000000 and timestamp < 20150427000000 group by event_errorText
[2] select event_errorText, count(*) from MobileWebEditing_8599025 where event_action = 'error' and timestamp > 20150401000000 and timestamp < 20150427000000 and event_username is NULL group by event_errorText