Handle unmappable Slack user identifiers

src/ctp_slack_bot/services/slack_service.py

@@ -74,9 +74,10 @@ class SlackServiceResource(AsyncResource):
     async def init(self: Self, event_brokerage_service: EventBrokerageService, slack_bolt_app: AsyncApp) -> SlackService:
         match await slack_bolt_app.client.users_list():
             case AsyncSlackResponse(status_code=200, data={"ok": True, "members": users}):
-                user_id_name_map = {user["id"]: user["profile"]["display_name"] or user["real_name"]
-                                    for user
-                                    in users}
+                user_id_name_map = {id: display_name
+                                    for id, display_name
+                                    in zip(map(SlackServiceResource._get_user_id, users), map(SlackServiceResource._get_user_display_name, users))
+                                    if display_name}
                 logger.debug("Obtained a list of {} user name(s) for the workspace: {}", len(user_id_name_map), user_id_name_map)
             case something:
                 user_id_name_map = {}
@@ -84,3 +85,17 @@ class SlackServiceResource(AsyncResource):
         slack_service = SlackService(event_brokerage_service=event_brokerage_service, slack_bolt_app=slack_bolt_app, user_id_name_map=user_id_name_map)
         slack_service.initialize()
         return slack_service
+
+    @classmethod
+    def _get_user_id(cls, user: Mapping[str, Any]):
+        return user["id"]
+
+    @classmethod
+    def _get_user_display_name(cls, user: Mapping[str, Any]):
+        match user:
+            case {"profile": {"display_name": display_name}}:
+                return display_name
+            case {"real_name": real_name}:
+                return real_name
+            case _:
+                None