KeywordBear.py: Output appropriate message

Output appropriate message if the language
given in input is not valid/not supported
for KeywordBear

Fixes coala#1256

Author: Techievena

bears/general/KeywordBear.py

@@ -1,4 +1,5 @@
 import re
+import logging
 
 from coalib.bearlib import deprecate_settings
 from coalib.bears.LocalBear import LocalBear
@@ -18,8 +19,12 @@ def _get_comments(dependency_results):
             not isinstance(annotation_bear_results, list)):
         return
 
-    for result in annotation_bear_results:
-        yield from result.contents.get('comments', [])
+    try:
+        for result in annotation_bear_results:
+            yield from result.contents.get('comments', [])
+    except AttributeError:
+        logging.error(result.contents)
+        return
 
 
 def generate_diff(comments, file, filename,

tests/general/KeywordBearTest.py

@@ -214,3 +214,20 @@ def test_keyword_regex(self):
             self.assertEqual(result[0].message, 'The line contains the keyword'
                                                 " 'Issue #123' which resulted "
                                                 'in a match with given regex.')
+
+    def test_wrong_language(self):
+        section = Section('')
+        section.append(Setting('language', 'anything'))
+        section.append(Setting('keywords', 'TODO'))
+        uut = KeywordBear(section, Queue())
+        dep_results = {
+            'AnnotationBear': HiddenResult(
+                'coalang specification for anything not found.')
+        }
+
+        text = ['# todo 123']
+
+        with execute_bear(uut, 'F', text,
+                          dependency_results=dep_results) as result:
+            self.assertEqual(
+                result.contents, 'coalang specification for anything not found.')