[ament_cppcheck] Report errors from additional includes (#216)

* [ament_cppcheck] Report errors from additional includes

Before, if an error was found in an additional include we get a KeyError exception.

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

* Use defaultdict

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

ament_cppcheck/ament_cppcheck/main.py

@@ -158,7 +158,8 @@ def main(argv=sys.argv[1:]):
         return 1
 
     # output errors
-    report = {}
+    report = defaultdict(list)
+    # even though we use a defaultdict, explicity add known files so they are listed
     for filename in files:
         report[filename] = []
     for error in root.find('errors'):