fix empty colon in query from selecting Chinese

searx/query.py

@@ -77,7 +77,7 @@ class RawTextQuery:
                     pass
 
             # this force a language
-            if query_part[0] == ':':
+            if query_part[0] == ':' and len(query_part) > 1:
                 lang = query_part[1:].lower().replace('_', '-')
 
                 # check if any language-code is equal with

tests/unit/test_query.py

@@ -59,6 +59,15 @@ class TestQuery(SearxTestCase):
         self.assertEqual(len(query.languages), 0)
         self.assertFalse(query.specific)
 
+    def test_empty_colon_in_query(self):
+        query_text = 'the : query'
+        query = RawTextQuery(query_text, [])
+
+        self.assertEqual(query.getFullQuery(), query_text)
+        self.assertEqual(len(query.query_parts), 0)
+        self.assertEqual(len(query.languages), 0)
+        self.assertFalse(query.specific)
+
     def test_timeout_below100(self):
         query_text = '<3 the query'
         query = RawTextQuery(query_text, [])