fix: made evidence be declared as None if there is no evidence given

shortmute/shortmute.py

@@ -52,6 +52,8 @@ class Shortmute(commands.Cog):
             evidence = evidence_link
         elif evidence_image:
             evidence = str(evidence_image)
+        else:
+            evidence = None
         immune_roles_list = await self.config.guild(interaction.guild).immune_roles()
         for role_id in immune_roles_list:
             role = interaction.guild.get_role(role_id)