bad_error5.lean:13:10: error: don't know how to synthesize placeholder
context:
c : S
⊢ Type ?
bad_error5.lean:13:10: error: failed to add declaration '_interaction' to environment, value has metavariables
remark: set 'formatter.hide_full_terms' to false to see the complete term
  …
bad_error5.lean:9:11: warning: declaration 'V' uses sorry
