changes in water level updating when tank height received is zero

src/controllers/tanksController.js

@@ -4796,7 +4796,7 @@ client.on('message', async (topic, message) => {
         const waterLevel = parseInt(waterLevelHeight * waterCapacityPerCm, 10); // Calculated water level
 
         // Update water level in the existing tank
-        if (waterLevel >= 0) {
+        if (tankHeight>0 && waterLevel >= 0) {
           existingTank.waterlevel = waterLevel;
           await existingTank.save();