error_pos.lean:1:39: error: type expected at
  B
error_pos.lean:4:43: error: type expected at
  B
error_pos.lean:9:39: error: type expected at
  B
λ (A : Type) (B : A → Type) (b : sorry), true : Π (A : Type), (A → Type) → sorry → Prop
error_pos.lean:11:35: error: type expected at
  B
λ (A : Type) (B : A → Type), sorry → true : Π (A : Type), (A → Type) → Prop
error_pos.lean:13:42: error: type expected at
  B
λ (A : Type) (B : A → Type) (b : sorry), b : Π (A : Type), (A → Type) → sorry → sorry
error_pos.lean:15:105: error: invalid let-expression, expression
  a₁
has type
  B
but is expected to have type
  A
error_pos.lean:15:133: error: invalid let-expression, expression
  a₂
has type
  B
but is expected to have type
  A