Fix crash when file fails to tokenize but parses

src/flake8/checker.py

@@ -597,6 +597,7 @@ class FileChecker(object):
         """Run checks against the file."""
         try:
             self.process_tokens()
+            self.run_ast_checks()
         except exceptions.InvalidSyntax as exc:
             self.report(
                 exc.error_code,
@@ -605,8 +606,6 @@ class FileChecker(object):
                 exc.error_message,
             )
 
-        self.run_ast_checks()
-
         logical_lines = self.processor.statistics["logical lines"]
         self.statistics["logical lines"] = logical_lines
         return self.filename, self.results, self.statistics

tests/integration/test_main.py

@@ -85,3 +85,17 @@ Configured `per-file-ignores` setting:
     incorrect/*
     values/*
 '''  # noqa: E501
+
+
+def test_tokenization_error_but_not_syntax_error(tmpdir, capsys):
+    """Test that flake8 does not crash on tokenization errors."""
+    with tmpdir.as_cwd():
+        # this is a crash in the tokenizer, but not in the ast
+        tmpdir.join('t.py').write("b'foo' \\\n")
+
+        app = application.Application()
+        app.run(['t.py'])
+
+    out, err = capsys.readouterr()
+    assert out == 't.py:1:1: E902 TokenError: EOF in multi-line statement\n'
+    assert err == ''