Update slothy/helper.py

Co-authored-by: Hanno Becker <[email protected]>

slothy/helper.py

@@ -783,6 +783,7 @@ def prepare_value(a):
             return a
 
         def apply_arg(l, arg, val):
+            # This function is also called on the values of tags, which may not be strings.
             if isinstance(l, str) is False:
                 return l
             l = re.sub(f"\\\\{arg}\\\\\\(\\)", val, l)