Null Check on AnimationClips

[Michael-Schaer]

Line 647 misses a null check:

Original:

if (m != null) 
{
  AnimationClip clip = m as AnimationClip;

  EditorCurveBinding[] ecbs = AnimationUtility.GetObjectReferenceCurveBindings(clip);

Fixed:

if (m != null)
{
  AnimationClip clip = m as AnimationClip;

  if (clip != null)
  {
    EditorCurveBinding[] ecbs = AnimationUtility.GetObjectReferenceCurveBindings(clip);

Thx for sharing this very useful Asset!