fix remove round used in sector

src/warchron/model/campaign.py

@@ -269,10 +269,13 @@ class Campaign:
 
     def remove_round(self, round_id: str) -> None:
         rnd = next((r for r in self.rounds if r.id == round_id), None)
+        for sect in self.sectors.values():
+            if sect.round_id == round_id:
+                sect.round_id = None
         if rnd:
             self.rounds.remove(rnd)
 
-    def get_round_index(self, round_id: str) -> int:
+    def get_round_index(self, round_id: str | None) -> int | None:
         if round_id is None:
             return None
         for index, rnd in enumerate(self.rounds, start=1):

src/warchron/model/model.py

@@ -380,7 +380,9 @@ class Model:
                         return rnd
         raise KeyError("Round not found")
 
-    def get_round_index(self, round_id: str) -> int:
+    def get_round_index(self, round_id: str | None) -> int | None:
+        if round_id is None:
+            return None
         camp = self.get_campaign_by_round(round_id)
         return camp.get_round_index(round_id)
 

src/warchron/model/sector.py

@@ -7,14 +7,14 @@ class Sector:
     def __init__(
         self,
         name: str,
-        round_id: str,
+        round_id: str | None,
         major_id: str | None,
         minor_id: str | None,
         influence_id: str | None,
     ):
         self.id: str = str(uuid4())
         self.name: str = name
-        self.round_id: str = round_id
+        self.round_id: str | None = round_id
         self.major_objective_id: str | None = major_id  # ref to War.objectives
         self.minor_objective_id: str | None = minor_id  # ref to War.objectives
         self.influence_objective_id: str | None = influence_id  # ref to War.objectives