How to stop camera from spazzing out?

Hey again,

I have an 'Orbit Camera' C# script that I grabbed from the wiki, and modified it a little.

The camera starts spazzing out when the camera is under the ground(plane) or when the camera is in a wall(cube). I tried to resolve it by adding a minimum distance in which the camera can be: if (distance > distanceMin) distance -= hit.distance;, but it didn't fully work, although it did help a little.

Right now I have this code:

 RaycastHit hit;
 if (Physics.Linecast(target.position, transform.position, out hit))
 {
     
     if (!resetCam)
         oldDist = distance;
     
     if (distance > distanceMin)
         distance -= hit.distance;
 
     // Just some odd debug.
     if (Input.GetButton("Jump"))
         Debug.Log(distance);
     
     resetCam = true;
 }
 else
 {
     if (resetCam)
     {
         distance = oldDist;
         resetCam = false;
     }
 }

And after that, I'm setting the camera's position with:

 Vector3 position = rotation * new Vector3(0.0f, 0.0f, -distance) + target.position;
 
 transform.position = position;

If you could, please don't just write out the code/answer as it would be helpful if you explain your answer so that I can avoid making this mistake again. Please tell me if you need more code or a better explanation of what's the error. And tell me if you want a web player version to see it for yourself.

A short 6 second video that's showing what is happening. (Note: Click the MP4 button at the top of the page.)

Thank you,

SeeSharp.