2D Radar Rotate

Hello, there I'm having a bit of trouble
.
I used code that I found on Unity Tutorial, about rotating around a pivot point, from point A to point B.
I understand the basic concept of Rotation.

Code (CSharp):

1. int angle = (int)pivot.transform.eulerAngles.z;
2.  
3. void Start(){
4. pivot.transform.Rotate(0.0f, 0.0f, Random.Range(-70.0f,70.0f));
5. //Sets starting point Random between -70 and 70 degrees
6.  
7. }
8.  
9. void Update(){
10.         int angle = (int)pivot.transform.eulerAngles.z;
11.  
12.         if (angle > 80 || angle < -80)
13.         angle -= 360;
14.  
15.         if ((angle <= -80) || (angle >= 80))
16.         direction *= -1f; // reverse direction of radar
17.  
18.         pivot.transform.Rotate (0, speed * direction * Time.deltaTime);
19. }
20.  

https://ibb.co/k4pzLm

What I want is for red laser to rotate from Current position 0 to 90, and then from 90 back to -90 etc.Like a radar would do.
This code manages to do that but gets stuck sometimes at 81f. Is there a better way to do this?

And I noticed angle in Editor is shown like from 0 to 90 and from 0 to -90. While in play mode it's from 0 to 90 and when I want it to go back it's from 0 to 270.Does that affect it?

I'm making some basic mobile game, so any help or tip would be appreciated. Thanks