ctx_error_msgs.lean:4:0: error: infer type failed, function expected at
  f a
term
  f
has type
  ℕ
state:
f a : ℕ
⊢ true
ctx_error_msgs.lean:11:0: error: infer type failed, unknown variable
  a
state:
⊢ true
ctx_error_msgs.lean:18:0: error: infer type failed, incorrect number of universe levels
  eq
state:
a : ℕ
⊢ true
ctx_error_msgs.lean:23:0: error: infer type failed, incorrect number of universe levels
  eq.{0 0}
state:
a : ℕ
⊢ true