Coherce empty locale to string

calendarweek/util.py

@@ -3,7 +3,7 @@ from typing import Optional
 
 
 def normalise_locale(loc: str, enc: Optional[str] = None) -> str:
-    loc = locale_alias.get(loc, loc)
+    loc = locale_alias.get(loc, loc) or ""
     if loc:
         if enc:
             enc = locale_encoding_alias.get(enc.replace("-", ""), enc)