Don't punish users when no profanity gets detected

The automatic profanity detection in ModBot contained a bug, which
resulted in a false-positive profanity detection for every text in
that language, if the detected language didn't have any profanity terms
configured. This commit fixes that, by returning when no profanity terms
for the detected language are configured.

xpartamupp/modbot.py

@@ -529,6 +529,9 @@ async def _muc_check_profanity(self, msg: Message) -> None:
                     select(ProfanityTerms.term).filter(ProfanityTerms.language.in_(languages))
                 ).scalars()
             )
+            if not profanity_terms:
+                return
+
             offending_terms = re.findall(
                 r"(?:^|(?<= ))(" + "|".join(profanity_terms) + r")(?= |$)",
                 " ".join(tokens_lemmatized),