Fix #246: No error subtitle when no bridge type is available

src/bridge_gui.cpp

@@ -434,10 +434,10 @@ void ShowBuildBridgeWindow(TileIndex start, TileIndex end, TransportType transpo
 		}
 
 		bool any_available = false;
-		CommandCost type_check;
+		StringID type_errmsg = INVALID_STRING_ID;
 		/* loop for all bridgetypes */
 		for (BridgeType brd_type = 0; brd_type != MAX_BRIDGES; brd_type++) {
-			type_check = CheckBridgeAvailability(brd_type, bridge_len);
+			CommandCost type_check = CheckBridgeAvailability(brd_type, bridge_len);
 			if (type_check.Succeeded()) {
 				/* Re-check bridge building possibility is initial bridge builindg query indicated a bridge type dependent failure */
 				if (query_per_bridge_type && DoCommand(end, start, type | brd_type, CommandFlagsToDCFlags(GetCommandFlags(CMD_BUILD_BRIDGE)) | DC_QUERY_COST, CMD_BUILD_BRIDGE).Failed()) continue;
@@ -449,13 +449,12 @@ void ShowBuildBridgeWindow(TileIndex start, TileIndex end, TransportType transpo
 				 * bridge itself (not computed with DC_QUERY_COST) */
 				item.cost = ret.GetCost() + (((int64)tot_bridgedata_len * _price[PR_BUILD_BRIDGE] * item.spec->price) >> 8) + infra_cost;
 				any_available = true;
+			} else if (type_check.GetErrorMessage() != INVALID_STRING_ID) {
+				type_errmsg = type_check.GetErrorMessage();
 			}
 		}
 		/* give error cause if no bridges available here*/
-		if (!any_available)
-		{
-			errmsg = type_check.GetErrorMessage();
-		}
+		if (!any_available && type_errmsg != INVALID_STRING_ID) errmsg = type_errmsg;
 	}
 
 	if (bl != nullptr && bl->size() != 0) {