Check EngineHelper for null in SSLSocket.close()

[cconlon]

This PR adds null pointer checking to WolfSSLSocket, specifically for the issue in close() where this.EngineHelper.clearObjectState(); could have been called in some scenarios if this.EngineHelper had already been set to null.

A regression test has also been added as part of this PR.

[Copilot]

Pull Request Overview

This PR addresses a potential null pointer exception in the WolfSSLSocket.close() method by adding null checks for the EngineHelper field before accessing it. The fix prevents NPEs that could occur if EngineHelper was already set to null or if the constructor failed after partial initialization.

• Added null pointer checks around EngineHelper method calls in close() and checkAndInitSSLSocket()
• Added a regression test that simulates the scenario using reflection to set EngineHelper to null

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/java/com/wolfssl/provider/jsse/WolfSSLSocket.java	Added null checks for EngineHelper in close() and checkAndInitSSLSocket() methods
src/test/com/wolfssl/provider/jsse/test/WolfSSLSocketTest.java	Added regression test to verify close() handles null EngineHelper without throwing NPE