Problem with Constraint Camera Rotation C#

 using UnityEngine;
 using System.Collections;
 
 public class ConstraintRotation : MonoBehaviour {
     public enum ConstraintAxis{X = 0, Y, Z};
 
     public ConstraintAxis axis;             // Rotation around this axis is constrained
     public float min;                        // Relative value in degrees
     public float max;                        // Relative value in degrees
     private Transform thisTransform;
     private Vector3 rotateAround;
     private Quaternion minQuaternion;
     private Quaternion maxQuaternion;
     private float range;
     
     void Start()
     {
         thisTransform = transform;
         
         // Set the axis that we will rotate around
         switch ( axis )
         {
         case ConstraintAxis.X:
             rotateAround = Vector3.right;
             break;
             
         case ConstraintAxis.Y:
             rotateAround = Vector3.up;
             break;
             
         case ConstraintAxis.Z:
             rotateAround = Vector3.forward;
             break;
         }
         
         // Set the min and max rotations in quaternion space
         var axisRotation = Quaternion.AngleAxis( thisTransform.localRotation.eulerAngles[ axis ], rotateAround );
         minQuaternion = axisRotation * Quaternion( min, rotateAround );
         maxQuaternion = axisRotation * Quaternion.AngleAxis( max, rotateAround );
         range = max - min;
     }
     
     // We use LateUpdate to grab the rotation from the Transform after all Updates from
     // other scripts have occured
     void LateUpdate() 
     {
         // We use quaternions here, so we don't have to adjust for euler angle range [ 0, 360 ]
         var localRotation = thisTransform.localRotation;
         var axisRotation = Quaternion.AngleAxis( localRotation.eulerAngles[ axis ], rotateAround );
         var angleFromMin = Quaternion.Angle( axisRotation, minQuaternion );
         var angleFromMax = Quaternion.Angle( axisRotation, maxQuaternion );
         
         if ( angleFromMin <= range && angleFromMax <= range )
             return; // within range
         else
         {        
             // Let's keep the current rotations around other axes and only
             // correct the axis that has fallen out of range.
             var euler = localRotation.eulerAngles;            
             if ( angleFromMin > angleFromMax )
                 euler[ axis ] = maxQuaternion.eulerAngles[ axis ];
             else
                 euler[ axis ] = minQuaternion.eulerAngles[ axis ];
             
             thisTransform.localEulerAngles = euler;        
         }
     }
 }

this is my code, and the Console is saying some errors

The best overloaded method match for UnityEngine.Vector3.this[int]' has some invalid arguments Argument #1' cannot convert ConstraintRotation.ConstraintAxis' expression to type int'

The best overloaded method match for `UnityEngine.Quaternion.AngleAxis(float, UnityEngine.Vector3)' has some invalid arguments

Can someone help me? It's a script to Constraint X rotation of the main camera.