Fix SendHeartbeat crash when HTTP module is unloaded during engine shutdown

[Copilot]

What this PR does / why we need it:

FGSDKInternal::SendHeartbeat() can crash via nullptr dereference on FHttpModule::Get().CreateRequest() when the HTTP module has already been unloaded during engine shutdown. The heartbeat runs on an async thread, so depending on timing, it may attempt to access the HTTP module after the GameThread has unloaded it.

Adds an IsModuleLoaded guard at the top of SendHeartbeat():

if (!FModuleManager::Get().IsModuleLoaded(TEXT("HTTP")))
{
    UE_LOG(LogPlayFabGSDK, Warning, TEXT("HTTP module is not loaded, skipping heartbeat."));
    return;
}

Applied to both UnrealPlugin/Source/ and UnrealPlugin/TestingProject/Plugins/ copies.

Special notes for your reviewer:

As noted in the issue, there is a theoretical TOCTOU race between the IsModuleLoaded check and the subsequent FHttpModule::Get() call. In practice, the window is negligibly small and this is the standard UE pattern for this class of problem. A fully thread-safe solution would require architectural changes to the heartbeat lifecycle (e.g., preventing module unload until the heartbeat thread exits), which is out of scope here.

If applicable:

• this PR contains documentation
• this PR contains unit tests
• this PR has been tested for backwards compatibility

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Unreal: FGSDKInternal::SendHeartbeat() may crash after the engine's shutdown phase because the HTTP module is unloaded</issue_title>
<issue_description>Hi,

Describe the bug

FGSDKInternal::SendHeartbeat() may crash after the engine's shutdown phase.
Because this happens in async code, this does not always occur, depending on timings.

The crash occurs due to a nullptr dereference at the line FHttpModule::Get().CreateRequest() in FGSDKInternal::SendHeartbeat(), after the engine's shutdown phase (when the game server requests exits and all modules are unloaded).
The only way this could happen would be because the HTTP module is unloaded, and because we're in the shutdown phase, the module is not allowed to be loaded again.

To prevent this, the following snippet could be inserted at the beginning of FGSDKInternal::SendHeartbeat():

	if (!FModuleManager::Get().IsModuleLoaded(TEXT("HTTP")))
		return;

However, it would still not be thread-safe: it's technically possible for the HTTP module to be unloaded on the GameThread at the exact same time it is accessed from the async thread.

To Reproduce

1. Run any dedicated server built with Unreal Engine and the PlayFab GSDK; For this, use PlayFab's LocalMultiplayerAgent tool.
2. Make the server exit normally (one way to do this is FGenericPlatformMisc::RequestExit(false))
3. The aforementioned crash may occur because FHttpModule::Get() returns nullptr.
   </issue_description>

<agent_instructions>can you check if this has been fixed?</agent_instructions>

Comments on the Issue (you are Copilot in this section)

• Fixes Unreal: FGSDKInternal::SendHeartbeat() may crash after the engine's shutdown phase because the HTTP module is unloaded #153

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[Copilot]

Pull request overview

This PR updates the Unreal PlayFab GSDK plugin’s async heartbeat sender to avoid crashing during engine shutdown when Unreal’s HTTP module has already been unloaded.

Changes:

• Added an IsModuleLoaded("HTTP") guard in FGSDKInternal::SendHeartbeat() to skip sending heartbeats if the HTTP module is unavailable.
• Applied the same change to both the main plugin source and the TestingProject plugin copy.

Reviewed changes

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

File	Description
UnrealPlugin/Source/PlayFabGSDK/Private/GSDKInternal.cpp	Adds an HTTP-module-loaded check before creating heartbeat HTTP requests to avoid shutdown-time null deref.
UnrealPlugin/TestingProject/Plugins/PlayFabGSDK/Source/PlayFabGSDK/Private/GSDKInternal.cpp	Mirrors the same shutdown guard change in the TestingProject plugin copy.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (2)

UnrealPlugin/TestingProject/Plugins/PlayFabGSDK/Source/PlayFabGSDK/Private/GSDKInternal.cpp:211

• If the HTTP module unloads before this async heartbeat thread exits, this path can execute every heartbeat interval until FGSDKInternal is destroyed, producing repeated Warning logs during engine shutdown. Consider downgrading to Verbose (or logging once) and stopping the heartbeat loop when the module is missing to avoid log spam and needless work.

	FHttpModule* HttpModule = FModuleManager::Get().GetModulePtr<FHttpModule>(TEXT("HTTP"));
	if (!HttpModule)
	{
		UE_LOG(LogPlayFabGSDK, Warning, TEXT("HTTP module is not loaded, skipping heartbeat."));
		return;

UnrealPlugin/Source/PlayFabGSDK/Private/GSDKInternal.cpp:211

• If the HTTP module unloads before this async heartbeat thread exits, this path can execute every heartbeat interval until FGSDKInternal is destroyed, producing repeated Warning logs during engine shutdown. Consider downgrading to Verbose (or logging once) and stopping the heartbeat loop when the module is missing to avoid log spam and needless work.

	FHttpModule* HttpModule = FModuleManager::Get().GetModulePtr<FHttpModule>(TEXT("HTTP"));
	if (!HttpModule)
	{
		UE_LOG(LogPlayFabGSDK, Warning, TEXT("HTTP module is not loaded, skipping heartbeat."));
		return;