simp only [x_eq_n, Array.mkEmpty_eq, h_range_size, Nat.lt_irrefl] at x_lt_n
x n : Nat
ih : ∀ (h : x < n), (Array.range n)[x] = x
h : x < n + 1
x_eq_n : x = n
x_lt_n : x < (Nat.fold (flip Array.push) n (Array.mkEmpty (n + 1))).size
h_range_size : (Nat.fold (flip Array.push) n #[]).size = n
⊢ False
no goals