Fix #10638: Incorrect water infra total when building canal over object

In the case where the object is on an unowned canal tile and
the new canal tile is owned

src/water_cmd.cpp

@@ -481,6 +481,14 @@ CommandCost CmdBuildCanal(DoCommandFlag flags, TileIndex tile, TileIndex start_t
 		if (!water) cost.AddCost(ret);
 
 		if (flags & DC_EXEC) {
+			if (IsTileType(current_tile, MP_WATER) && IsCanal(current_tile)) {
+				Owner owner = GetTileOwner(current_tile);
+				if (Company::IsValidID(owner)) {
+					Company::Get(owner)->infrastructure.water--;
+					DirtyCompanyInfrastructureWindows(owner);
+				}
+			}
+
 			switch (wc) {
 				case WATER_CLASS_RIVER:
 					MakeRiver(current_tile, Random());
@@ -498,14 +506,11 @@ CommandCost CmdBuildCanal(DoCommandFlag flags, TileIndex tile, TileIndex start_t
 					FALLTHROUGH;
 
 				default:
-					/* If we overbuild a water object with a canal, don't update the infrastructure total. */
-					bool is_existing_canal = IsTileType(current_tile, MP_WATER) && IsCanal(current_tile);
-					if (Company::IsValidID(_current_company) && !is_existing_canal) {
+					MakeCanal(current_tile, _current_company, Random());
+					if (Company::IsValidID(_current_company)) {
 						Company::Get(_current_company)->infrastructure.water++;
 						DirtyCompanyInfrastructureWindows(_current_company);
 					}
-
-					MakeCanal(current_tile, _current_company, Random());
 					break;
 			}
 			MarkTileDirtyByTile(current_tile);