Do not crash if license is missing

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

src/cluecode/plugin_filter_clues.py

@@ -164,7 +164,12 @@ def from_scan_data(data):
             for a in detected_authors
         )
 
-        license_matches = list(chain.from_iterable(d['matches'] for d in data['license_detections']))
+        license_matches = list(
+            chain.from_iterable(
+                d.get('matches', [])
+                for d in data.get('license_detections', {})
+            )
+        )
 
         detections = Detections(
             copyrights=detected_copyrights,

tests/cluecode/test_plugin_filter_clues.py

@@ -58,7 +58,7 @@ def test_scan_plugin_filter_clues_does_not_filter_incorrectly():
 
 # Regression on types tracked in https://github.com/nexB/typecode/issues/21
 def test_scan_plugin_filter_clues_for_license():
-    # this test fies is a copy of pcre.LICENSE that contains
+    # this test file is a copy of pcre.LICENSE that contains
     # several emails, authors, urls
     test_dir = test_env.get_test_loc('plugin_filter_clues/files/LICENSE3')
     result_file = test_env.get_temp_file('json')