fix: don't crash on unclosed brace in tuple inside map inside anonymous function (#125)

Author: katafrakt

lib/spitfire.ex

@@ -3804,6 +3804,10 @@ defmodule Spitfire do
     :eof
   end
 
+  defp peek_token(%{peek_token: nil}) do
+    :eof
+  end
+
   defp peek_token(%{tokens: :eot}) do
     :eof
   end

test/spitfire_test.exs

@@ -2439,6 +2439,11 @@ defmodule SpitfireTest do
                     ], [1]},
                    :ok
                  ]}, [{[line: 1, column: 1], "missing closing brace for tuple"}]}
+
+      code = "fn x -> %{a: {1,"
+
+      assert {:error, _ast, errors} = Spitfire.parse(code)
+      assert {[line: 1, column: 14], "missing closing brace for tuple"} in errors
     end
 
     test "missing closing map brace" do