Improve error message when event signup failed

3 jobs for 31-fix-blacklisted-error-message in 11 minutes and 23 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #209969
eslint

00:02:17

 
  Build
passed #209970
build_dev

00:08:52

 
  Deploy
passed #209971
deploy_dev

00:00:12