Fix client crash when firing at streamed-out vehicle wheels

[HeresHavi]

Summary

Added native vehicle and wheel index checks when custom weapons target vehicle wheels.
Streamed-out vehicles now use the vehicle element's cached position instead of trying to access missing wheel data.

Motivation

A streamed-out vehicle can still be a valid Lua element, but it no longer has a native GTA vehicle. Firing a custom weapon at one of its wheels tried to read the wheel position from that missing object and caused an access violation.

For example, a remote turret resource might keep targeting a car wheel as it drives away. If the car streams out before the turret fires again, the next shot could crash the player's client.

Crash Stack

Exception: Access violation (0xC0000005)

CClientWeapon::Fire (CClientWeapon.cpp:260)
CStaticFunctionDefinitions::FireWeapon (CStaticFunctionDefinitions.cpp:7718)
CLuaWeaponDefs::FireWeapon (CLuaWeaponDefs.cpp:195)

Reproduction

1. Created a client-side M4, a nearby control vehicle, and a vehicle far outside the streaming range.
2. Confirmed the weapon and control vehicle were streamed in while the far vehicle was a valid streamed-out element.
3. Targeted wheel 0 on the nearby vehicle and fired once. The client remained open.
4. Targeted wheel 0 on the streamed-out vehicle:

setWeaponTarget(weapon, streamedOutVehicle, 0)
fireWeapon(weapon)

Before the fix, fireWeapon immediately crashed the Debug client with the stack shown above.

Test plan

Runtime

• Before Fix: Firing at wheel 0 on a valid streamed-out vehicle crashed the Debug client in CClientWeapon::Fire.
• After Fix: The same target and shot returned true, and the client stayed open. Repeated shots and cleanup/recreation also passed.
• Valid Case: Firing at wheel 0 on a streamed-in vehicle still returned true.

Builds and Tests

• Debug | Win32: Build passed, 304 client tests passed.
• Release | Win32: Build passed, 304 client tests passed.
• Debug | x64: Server build passed.
• Ran clang-format.

Checklist

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