auto_quote_error2.lean:5:2: error: invalid apply tactic, failed to unify
  a = c
with
  ?m_2 = ?m_2
state:
a b c : ℕ,
a_1 : a = b,
a_2 : b = c
⊢ a = c

a b c : ℕ,
a_1 : a = b,
a_2 : b = c
⊢ Type ?
hello world
auto_quote_error2.lean:16:2: error: tactic failed, there are unsolved goals
state:
a b c : ℕ,
a_1 : a = b,
a_2 : b = c
⊢ a = c
hello world
auto_quote_error2.lean:28:2: error: tactic failed, there are unsolved goals
state:
a b c : ℕ,
a_1 : a = b,
a_2 : b = c
⊢ a = ?m_1
auto_quote_error2.lean:37:22: error: don't know how to synthesize placeholder
state:
a b c : ℕ,
h1 : a = b,
h2 : b = c
⊢ b = c