Program: 184204
Project: 184204
Buggy source:
public void update(){
  if (!isPlaying || !updateVertices)   return;
  currentTime=System.currentTimeMillis();
  KeyFrame currentFrame=frames[currentFrameIndex];
  KeyFrame nextFrame=frames[(currentFrameIndex + 1) % numFrames];
  float[] currentVerts=currentFrame.getVertices();
  float[] nextVerts=nextFrame.getVertices();
  float[] currentNormals=currentFrame.getNormals();
  float[] nextNormals=nextFrame.getNormals();
  int numVerts=currentVerts.length;
  float[] interPolatedVerts=new float[numVerts];
  float[] interPolatedNormals=new float[numVerts];
  for (int i=0; i < numVerts; i+=3) {
    interPolatedVerts[i]=currentVerts[i] + interpolation * (nextVerts[i] - currentVerts[i]);
    interPolatedVerts[i + 1]=currentVerts[i + 1] + interpolation * (nextVerts[i + 1] - currentVerts[i + 1]);
    interPolatedVerts[i + 2]=currentVerts[i + 2] + interpolation * (nextVerts[i + 2] - currentVerts[i + 2]);
    interPolatedNormals[i]=currentNormals[i] + interpolation * (nextNormals[i] - currentNormals[i]);
    interPolatedNormals[i + 1]=currentNormals[i + 1] + interpolation * (nextNormals[i + 1] - currentNormals[i + 1]);
    interPolatedNormals[i + 2]=currentNormals[i + 2] + interpolation * (nextNormals[i + 2] - currentNormals[i + 2]);
  }
  interpolation+=fps * (currentTime - startTime) / 1000;
  vertices().overwriteNormals(interPolatedNormals);
  vertices().overwriteVerts(interPolatedVerts);
  if (interpolation > 1) {
    interpolation=0;
    currentFrameIndex++;
    if (currentFrameIndex >= numFrames)     currentFrameIndex=0;
  }
  startTime=System.currentTimeMillis();
}

Fixed version (ground truth):
public void update(){
  if (!isPlaying || !updateVertices)   return;
  currentTime=System.currentTimeMillis();
  KeyFrame currentFrame=frames[currentFrameIndex];
  KeyFrame nextFrame=frames[(currentFrameIndex + 1) % numFrames];
  if (currentFrameName != null && !currentFrameName.equals(currentFrame.getName())) {
    if (!loop)     stop();
 else     currentFrameIndex=loopStartIndex;
    return;
  }
  float[] currentVerts=currentFrame.getVertices();
  float[] nextVerts=nextFrame.getVertices();
  float[] currentNormals=currentFrame.getNormals();
  float[] nextNormals=nextFrame.getNormals();
  int numVerts=currentVerts.length;
  float[] interPolatedVerts=new float[numVerts];
  float[] interPolatedNormals=new float[numVerts];
  for (int i=0; i < numVerts; i+=3) {
    interPolatedVerts[i]=currentVerts[i] + interpolation * (nextVerts[i] - currentVerts[i]);
    interPolatedVerts[i + 1]=currentVerts[i + 1] + interpolation * (nextVerts[i + 1] - currentVerts[i + 1]);
    interPolatedVerts[i + 2]=currentVerts[i + 2] + interpolation * (nextVerts[i + 2] - currentVerts[i + 2]);
    interPolatedNormals[i]=currentNormals[i] + interpolation * (nextNormals[i] - currentNormals[i]);
    interPolatedNormals[i + 1]=currentNormals[i + 1] + interpolation * (nextNormals[i + 1] - currentNormals[i + 1]);
    interPolatedNormals[i + 2]=currentNormals[i + 2] + interpolation * (nextNormals[i + 2] - currentNormals[i + 2]);
  }
  interpolation+=fps * (currentTime - startTime) / 1000;
  vertices().overwriteNormals(interPolatedNormals);
  vertices().overwriteVerts(interPolatedVerts);
  if (interpolation > 1) {
    interpolation=0;
    currentFrameIndex++;
    if (currentFrameIndex >= numFrames)     currentFrameIndex=0;
  }
  startTime=System.currentTimeMillis();
}