It seems the "Prettier / prettier"-check gives a false positive in some cases. The error message is as follows: Error: The process '/usr/bin/git' failed with exit code 1. As @danielUTM has pointed out, this problem can be avoided by doing the commit directly from the master-branch of the fork. For example, compare #2145 vs #2146 or #2130 vs #2148. But this workaround is not optimal so it would be good to have a proper solution.