fix: Add return statement missing in preprocessing function

app.py

@@ -28,6 +28,7 @@ def _remove_unk_chars(txt_list: List[str]):
     txt_list = [re.sub('\s+', ' ', tweet) for tweet in txt_list]
     txt_list = [re.sub("\'", "", tweet) for tweet in txt_list]
     txt_list = [deaccent(tweet).lower() for tweet in txt_list]
+    return txt_list
 
 def _remove_urls(txt_list: List[str]):
     url_regex = re.compile(