When merging a branch into e.g. master, I hit the Merge button. Then, to quickly find the latest commit on the branch which is to be merged, I use the top-left filter to filter on that branch.

When we decide to remove the branch after merging, an error message is raised with the following text:

'git log' failed with code 128:'fatal: bad revision 'aaaa'
'

where aaaa is the name of the branch which was just removed. This message keeps showing up every x seconds, probably because of auto refreshes.

When clicking Merge again and unset the filter on the branch (which actually doesn't exist anymore), the error messages disappear.

To summarize, these instructions can be followed to reproduce:

• switch to master
• create a branch, e.g. aaaa
• commit anything to that branch
• switch back to master
• click Merge
• filter on branch aaaa in the dialog where you pick the commit to merge
• cancel merge (or go ahead with the merge, doesn't matter)
• remove branch aaaa (force if you cancelled the merge)

To get rid of the messages:

• click Merge
• filter on branch 'All branches'