Fix dictionary changed size during iteration while converting levels map (#146)

* Resolve dictionary changed size during iteration while converting levels mapping and remove non-converted entry to avoid duplicate entires (str and int index).
Add default for premium sub count.

* Update disco/bot/bot.py

Co-Authored-By: Andrei Zbikowski <b1naryth1ef@users.noreply.github.com>

disco/bot/bot.py

@@ -189,7 +189,8 @@ class Bot(LoggingClass):
         # Convert our configured mapping of entities to levels into something
         #  we can actually use. This ensures IDs are converted properly, and maps
         #  any level names (e.g. `role_id: admin`) map to their numerical values.
-        for entity_id, level in six.iteritems(self.config.levels):
+        for entity_id, level in list(six.iteritems(self.config.levels)):
+            del self.config.levels[entity_id]
             entity_id = int(entity_id) if str(entity_id).isdigit() else entity_id
             level = int(level) if str(level).isdigit() else get_enum_value_by_name(CommandLevels, level)
             self.config.levels[entity_id] = level

disco/types/guild.py

@@ -338,7 +338,7 @@ class Guild(SlottedModel, Permissible):
     voice_states = AutoDictField(VoiceState, 'session_id')
     member_count = Field(int)
     premium_tier = Field(int)
-    premium_subscription_count = Field(int)
+    premium_subscription_count = Field(int, default=0)
     vanity_url_code = Field(text)
     max_presences = Field(int)
     max_members = Field(int)