Correct some parameter usage, handle errors if searches return nothing.

.vscode/settings.json

@@ -10,8 +10,8 @@
         "ondelete"
     ],
     "python.analysis.diagnosticSeverityOverrides": {
-        "reportOptionalMemberAccess": false,
+        "reportOptionalMemberAccess": "warning",
         "reportArgumentType": "information",
         "reportAttributeAccessIssue": "warning"
     }
-}
+}

cogs/commands/set.py

@@ -52,8 +52,10 @@ class SetCog(commands.Cog, name="Set command."):
                 .where(col(CategoryGroup.guild_id) == interaction.guild_id)
                 .where(col(CategoryGroup.id) == int(group_id))
             )
-            group = session.scalar(stmt)
-            group.ChannelId = channel_id
+            if (group := session.scalar(stmt)) is None:
+                await interaction.response.send_message("Group or Category was not found.", ephemeral=True)
+                return
+            group.channel_id = channel_id
             session.commit()
         await interaction.send(f"Registered <#{channel_id}>.", ephemeral=True)
 
@@ -88,8 +90,11 @@ class SetCog(commands.Cog, name="Set command."):
                 .where(col(CategoryGroup.guild_id) == interaction.guild_id)
                 .where(col(CategoryGroup.id) == int(group_id))
             )
-            group = session.scalar(stmt)
-            group.PadLength = length
+            if (group := session.scalar(stmt)) is None:
+                await interaction.response.send_message("Group or Category was not found.", ephemeral=True)
+                return
+
+            group.pad_length = length
             session.commit()
             await interaction.response.send_message(
                 f"Category pad length set to {length} for {group.name}", ephemeral=True
@@ -120,7 +125,9 @@ class SetCog(commands.Cog, name="Set command."):
 
         with Session(engine) as session:
             stmt = select(Guild).where(col(Guild.id) == interaction.guild_id)
-            guild = session.scalar(stmt)
+            if (guild := session.scalar(stmt)) is None:
+                await interaction.response.send_message("Guild was not found.", ephemeral=True)
+                return
             guild.submission_channel = channel_id
             session.commit()
         await interaction.send(f"Registered <#{channel_id}>.", ephemeral=True)
@@ -150,8 +157,11 @@ class SetCog(commands.Cog, name="Set command."):
                 .where(col(CategoryGroup.guild_id) == interaction.guild_id)
                 .where(col(CategoryGroup.id) == int(group_id))
             )
-            group = session.scalar(stmt)
-            group.UsernameLength = length
+            if (group := session.scalar(stmt)) is None:
+                await interaction.response.send_message("Group or Category was not found.", ephemeral=True)
+                return
+
+            group.username_length = length
             session.commit()
         await interaction.response.send_message(f"Username length set to {length}.", ephemeral=True)
 
@@ -178,7 +188,9 @@ class SetCog(commands.Cog, name="Set command."):
 
         with Session(engine) as session:
             stmt = select(Guild).where(col(Guild.id) == interaction.guild_id)
-            guild = session.scalar(stmt)
+            if (guild := session.scalar(stmt)) is None:
+                await interaction.response.send_message("Guild was not found.", ephemeral=True)
+                return
             guild.verification_channel = channel_id
             session.commit()
         await interaction.send(f"Registered <#{channel_id}>.", ephemeral=True)