Summary

• Fixed TypeError: Cannot read properties of null (reading 'setTRS') crash in VR mode
• getPosition() and getRotation() now correctly return null when grip data is not yet available, as documented
• Added defensive null checks in XrControllers script

Technical Details

The getPosition() and getRotation() methods had incorrect null guards:

// Before (broken)
getPosition() {
    if (!this._position) return null;  // _position is always initialized, never null
    this._updateTransforms();          // crashes when _localTransform is null
}

// After (fixed)
getPosition() {
    if (!this._grip) return null;      // correctly checks if grip data exists
    this._updateTransforms();
}

The crash occurred when getPosition() was called before the first valid gripPose was received from WebXR. The _localTransform matrix is only created when _grip becomes true, but the old guard checked _position which is always a valid Vec3.

This aligns the implementation with the existing JSDoc contract: "Get the world space position of input source if it is handheld (grip is true). Otherwise it will return null."

Checklist

• I have read the contributing guidelines
• My code follows the project's coding standards
• This PR focuses on a single change