Fixing https://github.com/wso2/product-iots/issues/1553 and https://github.com/wso2/product-iots/issues/1546

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/service/DeviceManagementProviderServiceImpl.java

@@ -558,7 +558,7 @@ public class DeviceManagementProviderServiceImpl implements DeviceManagementProv
             DeviceManagementDAOFactory.closeConnection();
         }
 
-        if (requireDeviceInfo) {
+        if (!allDevices.isEmpty() && requireDeviceInfo) {
             return this.getAllDeviceInfo(allDevices);
         }
         return allDevices;