message: fix: keyframes may not valid after __changeFinalValue
diff: @@ -509,11 +509,17 @@ class Track {
  }
  frameIdx = Math.min(frameIdx - 1, kfsNum - 2);
  }
  + let nextFrame = keyframes[frameIdx + 1];
  + let frame = keyframes[frameIdx];
  +
  + // Defensive coding.
  + if (!(frame && nextFrame)) {
  + return;
  + }
  +
  this._lastFrame = frameIdx;
  this._lastFramePercent = percent;
  - let nextFrame = keyframes[frameIdx + 1];
  - let frame = keyframes[frameIdx];
  const range = (nextFrame.percent - frame.percent);
  if (range === 0) {
  