correct() updated to only return positive match, otherwise None is returned

Author: bugsyb

language_tool_python/utils.py

@@ -113,18 +113,21 @@ def correct(text: str, matches: List[Match]) -> str:
     """
     ltext = list(text)
     matches = [match for match in matches if match.replacements]
-    errors = [ltext[match.offset:match.offset + match.errorLength]
-              for match in matches]
-    correct_offset = 0
-    for n, match in enumerate(matches):
-        frompos, topos = (correct_offset + match.offset,
-                          correct_offset + match.offset + match.errorLength)
-        if ltext[frompos:topos] != errors[n]:
-            continue
-        repl = match.replacements[0]
-        ltext[frompos:topos] = list(repl)
-        correct_offset += len(repl) - len(errors[n])
-    return ''.join(ltext)
+    if matches:
+        errors = [ltext[match.offset:match.offset + match.errorLength]
+                  for match in matches]
+        correct_offset = 0
+        for n, match in enumerate(matches):
+            frompos, topos = (correct_offset + match.offset,
+                              correct_offset + match.offset + match.errorLength)
+            if ltext[frompos:topos] != errors[n]:
+                continue
+            repl = match.replacements[0]
+            ltext[frompos:topos] = list(repl)
+            correct_offset += len(repl) - len(errors[n])
+        return ''.join(ltext)
+    else:
+        return None
 
 
 def get_language_tool_download_path() -> str: