Improve error message for unexpectedly repeated fields

2 jobs for master in 52 minutes and 55 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Build
passed compilation #705399
compile

00:15:54

 
  Test
failed testing #705400
test spec2

00:37:00

 
Name Stage Failure
failed
testing Test There is an unknown failure, please try again
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