Having the same issue; same error is coming up with bas_bon_20.png :/
Problem is the code is trying to get " bas_bon_20" instead "bas_bon_20", with the blank space at the start (which is a tab iirc):
that "\t" shouldn't be there.
To fix it, either go to www\data\CommonEvents.json, open it with an editor (notepad++ for example), remove word wrap, line 47, remove the \t and save.
You can also grab the attached file and replace it, but backup yours first just in case.