Fix #240: Allow errors on empty files

The noqa check crashes when the file is empty. The soultion is to not
check for noqa when the file is empty -- if it's empty, the user might
not possibly put any #noqa comments in there.

2 files changed, 2 insertions, 1 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 6465cb3..413c134 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -5,6 +5,7 @@ Changelog
 1.x (unreleased)
 ----------------
 
+* Allow the checkers to report errors on empty files. (Issue #240)
 * Fix ignoring too many checks when ``--select`` is used with codes
   declared in a flake8 extension. (Issue #216)
 
diff --git a/pep8.py b/pep8.py
index e0035b3..11e9bcc 100755
--- a/pep8.py
+++ b/pep8.py
@@ -1344,7 +1344,7 @@ class Checker(object):
         for name, cls, _ in self._ast_checks:
             checker = cls(tree, self.filename)
             for lineno, offset, text, check in checker.run():
-                if not noqa(self.lines[lineno - 1]):
+                if not self.lines or not noqa(self.lines[lineno - 1]):
                     self.report_error(lineno, offset, text, check)
 
     def generate_tokens(self):