Fix server response closing

[cedricve]

Description

Pull Request Description

Title: Fix server response closing

Motivation and Context

The current implementation of the Device class assumes that the server response (servResp) is always non-nil before attempting to close its body. However, in cases where an error occurs and servResp is nil, calling servResp.Body.Close() will result in a runtime panic, which can cause the application to crash unexpectedly.

This pull request adds a nil check before attempting to close the server response body. This ensures that the connection is only reused if the server response is valid, thereby preventing potential runtime panics and improving the robustness of the code.

Changes Made

• Added a nil check for servResp before calling servResp.Body.Close() in the callMethodDo and SendSoap methods.
• This change is applied consistently across multiple instances in the Device.go file.

Why This Improves the Project

1. Prevents Runtime Panics: By ensuring that servResp is non-nil before attempting to close its body, we prevent potential runtime panics that could crash the application.
2. Improves Code Robustness: Adding these checks enhances the robustness and reliability of the code by handling edge cases more gracefully.
3. Maintains Connection Reuse: The change ensures that the connection reuse logic is maintained without risking application stability.

Overall, this change contributes to the stability and reliability of the project, making it safer for production use.