short circuit on ast error before tokenization error

tests/unit/test_exceptions.py

@@ -13,7 +13,6 @@ from flake8 import exceptions
             plugin_name="plugin_name",
             exception=ValueError("boom!"),
         ),
-        exceptions.InvalidSyntax(exception=ValueError("Unexpected token: $")),
         exceptions.PluginRequestedUnknownParameters(
             plugin={"plugin_name": "plugin_name"},
             exception=ValueError("boom!"),

tests/unit/test_file_checker.py

@@ -7,30 +7,6 @@ import flake8
 from flake8 import checker
 
 
-@mock.patch("flake8.processor.FileProcessor")
-def test_run_ast_checks_handles_SyntaxErrors(FileProcessor):  # noqa: N802,N803
-    """Stress our SyntaxError handling.
-
-    Related to: https://github.com/pycqa/flake8/issues/169
-    """
-    processor = mock.Mock(lines=[])
-    FileProcessor.return_value = processor
-    processor.build_ast.side_effect = SyntaxError(
-        "Failed to build ast", ("", 1, 5, "foo(\n")
-    )
-    file_checker = checker.FileChecker(__file__, checks={}, options=object())
-
-    with mock.patch.object(file_checker, "report") as report:
-        file_checker.run_ast_checks()
-
-        report.assert_called_once_with(
-            "E999",
-            1,
-            3,
-            "SyntaxError: Failed to build ast",
-        )
-
-
 @mock.patch("flake8.checker.FileChecker._make_processor", return_value=None)
 def test_repr(*args):
     """Verify we generate a correct repr."""