add testPyProjectTOMLSettingOfWrongType

Author: wyattscarpenter

test-data/unit/check-flags.test

@@ -2482,3 +2482,10 @@ A = Union[C, List]  # OK
 -- check_untyped_defs is False by default.
 def f():
     x: int = "no"  # N: By default the bodies of untyped functions are not checked, consider using --check-untyped-defs
+
+[case testPyProjectTOMLSettingOfWrongType]
+# E: Invalid error code(s): true
+[file pyproject.toml]
+\[tool.mypy]
+enable_error_code = true
+