If you make multiple syntax errors in a row, iex repeats the error output of the first mistake for the second and following errors.

gistfile1.txt

Erlang R16B01 (erts-5.10.2) [source-bdf5300] [async-threads:10] [hipe] [kernel-poll:false]

Interactive Elixir (0.10.1-dev) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> 1 + 3
4
...
iex(5)> a = "foo"
"foo"
iex(6)> 8 + a    
** (ArithmeticError) bad argument in arithmetic expression
    :erlang.+(8, "foo")
    erl_eval.erl:569: :erl_eval.do_apply/6
    src/elixir.erl:147: :elixir.eval_forms/3
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:112: IEx.Server.eval/4
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:52: IEx.Server.wait_input/1
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:63: IEx.Server.wait_input/1
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:31: IEx.Server.start/1

iex(6)> a:bad = "foo"
** (SyntaxError) iex:6: keyword argument must be followed by space after: a:
    :erlang.+(8, "foo")
    erl_eval.erl:569: :erl_eval.do_apply/6
    src/elixir.erl:147: :elixir.eval_forms/3
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:112: IEx.Server.eval/4
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:52: IEx.Server.wait_input/1
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:63: IEx.Server.wait_input/1
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:31: IEx.Server.start/1

iex(6)> 12foo = 8
** (SyntaxError) iex:6: syntax error before: foo
    :erlang.+(8, "foo")
    erl_eval.erl:569: :erl_eval.do_apply/6
    src/elixir.erl:147: :elixir.eval_forms/3
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:112: IEx.Server.eval/4
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:52: IEx.Server.wait_input/1
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:63: IEx.Server.wait_input/1
    /home/mnutter/src/elixir/lib/iex/lib/iex/server.ex:31: IEx.Server.start/1