keyfinder: Catch output from keyfinder-cli with no key

beetsplug/keyfinder.py

@@ -76,7 +76,14 @@ class KeyFinderPlugin(BeetsPlugin):
                                 item.path)
                 continue
 
-            key_raw = output.rsplit(None, 1)[-1]
+            try:
+                key_raw = output.rsplit(None, 1)[-1]
+            except IndexError:
+                # Sometimes keyfinder-cli returns 0 but with no key, usually when
+                # the file is silent or corrupt, so we log and skip.
+                self._log.error(u'no key returned for path: {0}', item.path)
+                continue
+
             try:
                 key = util.text_string(key_raw)
             except UnicodeDecodeError:

docs/changelog.rst

@@ -282,6 +282,8 @@ Fixes:
   :bug:`3773` :bug:`3774`
 * Fix a bug causing PIL to generate poor quality JPEGs when resizing artwork.
   :bug:`3743`
+* :doc:`plugins/keyfinder`: Catch output from ``keyfinder-cli`` that is missing key.
+  :bug:`2242`
 
 For plugin developers:
 

test/test_keyfinder.py

@@ -76,6 +76,16 @@ class KeyFinderTest(unittest.TestCase, TestHelper):
         item.load()
         self.assertEqual(item['initial_key'], 'F')
 
+    def test_no_key(self, command_output):
+        item = Item(path='/file')
+        item.add(self.lib)
+
+        command_output.return_value = util.CommandOutput(b"", b"")
+        self.run_command('keyfinder')
+
+        item.load()
+        self.assertEqual(item['initial_key'], None)
+
 
 def suite():
     return unittest.TestLoader().loadTestsFromName(__name__)