suddenly have 'nan, nan, nan' error

Iv been following etteski FPS tutorials and have had no problems so, but now im suddenly getting Nan errors even tho i only changed a non important thing i added into the script.

this is the 'mouseLookScript'

     var defaultCameraAngle : float = 60;
     @HideInInspector
     var currentTargetCameraAngle : float = 60;
     @HideInInspector
     var ratioZoom : float = 1;
     @HideInInspector
     var ratioZoomV : float;
     
     var clampDown = -70;
     var clampUp = 70;
      
     var ratioZoomSpeed : float = 0.2;
      
     var lookSensitivity : float = 5;
     @HideInInspector
     var yRotation : float;
     @HideInInspector
     var xRotation : float;
     @HideInInspector
     var currentYRotation : float;
     @HideInInspector
     var currentXRotation : float;
     @HideInInspector
     var yRotationV : float;
     @HideInInspector
     var xRotationV : float;
     var lookSmoothDamp : float = 0.1;
     @HideInInspector
     var currentAimRatio : float = 1;
     
     var headbobSpeed : float = 1;
     @HideInInspector
     var headbobStepCounter : float;
     var headbobAmountX : float = 1;
     var headbobAmountY : float = 1;
     @HideInInspector
     var parentLastPos : Vector3;
     var eyeHeightRatio : float = 0.9;
     
     function Awake ()
     {
         parentLastPos = transform.parent.position;
     }
      
     function Update () 
     {
         if (transform.parent.GetComponent(PlayerMovementScript).grounded)
             headbobStepCounter += Vector3.Distance(parentLastPos, transform.parent.position) * headbobSpeed;
         transform.localPosition.x = Mathf.Sin(headbobStepCounter) * headbobAmountX * currentAimRatio;
         transform.localPosition.y = (Mathf.Cos(headbobStepCounter * 2) * headbobAmountY * currentAimRatio) + (transform.parent.localScale.y * eyeHeightRatio) - (transform.parent.localScale.y / 2);
        
         parentLastPos = transform.parent.position;
      
         if (currentAimRatio == 1)
             ratioZoom = Mathf.SmoothDamp(ratioZoom, 1, ratioZoomV, ratioZoomSpeed);
         else
             ratioZoom = Mathf.SmoothDamp(ratioZoom, 0, ratioZoomV, ratioZoomSpeed);
            
         camera.fieldOfView = Mathf.Lerp(currentTargetCameraAngle, defaultCameraAngle, ratioZoom);
      
         yRotation += Input.GetAxis("Mouse X") * lookSensitivity * currentAimRatio;
         xRotation -= Input.GetAxis("Mouse Y") * lookSensitivity * currentAimRatio;
        
         xRotation = Mathf.Clamp(xRotation, clampDown, clampUp);
        
         currentXRotation = Mathf.SmoothDamp(currentXRotation, xRotation, xRotationV, lookSmoothDamp);
         currentYRotation = Mathf.SmoothDamp(currentYRotation, yRotation, yRotationV, lookSmoothDamp);
        
         transform.rotation = Quaternion.Euler(currentXRotation, currentYRotation, 0);
     }

the only thing i changed was a variable i added called pause that meant when i pressed Esc i couldn't rotate my view, t worked perfectly no Nan errors but when i removed it i got Nan errors even tho it wasn't part of the original script and didnt effect the part giving me Nan errors.

I get this: !CompareApproximately (SqrMagnitude (q), 1.0F) UnityEngine.Quaternion:Euler(Single, Single, Single) MouseLookScript:Update() (at Assets/script/Player/MouseLookScript.js:69)

And this:transform.rotation assign attempt for 'playerCamera' is not valid. Input rotation is { NaN, NaN, NaN, NaN }. UnityEngine.Transform:set_rotation(Quaternion) MouseLookScript:Update() (at Assets/script/Player/MouseLookScript.js:69)

I also have errors with my player movement script because i use this for rotation.

If somebody could help me find out whats causing the errors and a way to fix that would be really helpful.

Edit: i tried copying and pasting directly from etteskis resources but still get the error even when i didn't before, i really don't know why it suddenly popped up.

FIXED: I think it was just a bug with unity, its a good engine but has a few weird bugs.

anyways, i fixed it by creating a new project and copying all files from old project, that's all. it was than fixed. I guess the error was just strangely caused when i edited the script (i hadn't edited that script in a while). It would be handy if these kinda bugs were fixed