Revert "Merge pull request #15293 from schneems/schneems/generator-output-in-error"

This reverts commit 7466d6a9f989a1a8f90899b79b34f1152e440b7c, reversing
changes made to b850c4c540e8f0c15742f67c532f521a4a123655.

This was an accidental merge. A new PR will follow.

/cc @schneems