Remove all clips from animation by script

Hello,

How to remove all AnimationClips from Animation via script? The same as set Size in editor to 0 but from script. I'm trying do do so:

while ( animation.GetClipCount() > 0 )
    for (var state : AnimationState in animation) 
        if ( state )
        {
            animation.RemoveClip( state.clip );
            break;
        }

but the Unity crashes if there is a clip marked in editor as "None". Can't find out why is it so.

Is it another way? Or I'm doing something wrong?