Don't crash if build_tokens_line() returns None; issue #306

1 files changed, 4 insertions, 0 deletions

diff --git a/pep8.py b/pep8.py
index d638388..0fbe22d 100755
--- a/pep8.py
+++ b/pep8.py
@@ -1346,6 +1346,10 @@ class Checker(object):
         """Build a line from tokens and run all logical checks on it."""
         self.report.increment_logical_line()
         mapping = self.build_tokens_line()
+
+        if not mapping:
+            return
+
         (start_row, start_col) = mapping[0][1]
         start_line = self.lines[start_row - 1]
         self.indent_level = expand_indent(start_line[:start_col])