Program: 112476
Project: 112476
Buggy source:
@Override public boolean update(boolean overlap,int delta,int mouseX,int mouseY,boolean keyPressed,int trackPosition){
  if (overlap || trackPosition > hitObject.getEndTime()) {
    hitResult();
    return true;
  }
  if (isSpinning && !(keyPressed || GameMod.RELAX.isActive()))   isSpinning=false;
  deltaOverflow+=delta;
  float angleDiff=0;
  if (GameMod.AUTO.isActive()) {
    angleDiff=delta * AUTO_MULTIPLIER;
    isSpinning=true;
  }
 else   if (GameMod.SPUN_OUT.isActive() || GameMod.AUTOPILOT.isActive()) {
    angleDiff=delta * SPUN_OUT_MULTIPLIER;
    isSpinning=true;
  }
 else {
    float angle=(float)Math.atan2(mouseY - (height / 2),mouseX - (width / 2));
    if (!isSpinning && (keyPressed || GameMod.RELAX.isActive())) {
      lastAngle=angle;
      isSpinning=true;
      return false;
    }
    angleDiff=angle - lastAngle;
    if (Math.abs(angleDiff) > 0.01f)     lastAngle=angle;
 else     angleDiff=0;
  }
  if (angleDiff < -Math.PI)   angleDiff+=TWO_PI;
 else   if (angleDiff > Math.PI)   angleDiff-=TWO_PI;
  if (isSpinning)   deltaAngleOverflow+=angleDiff;
  while (deltaOverflow >= DELTA_UPDATE_TIME) {
    float deltaAngle=0;
    if (isSpinning) {
      deltaAngle=deltaAngleOverflow * DELTA_UPDATE_TIME / deltaOverflow;
      deltaAngleOverflow-=deltaAngle;
      deltaAngle=Utils.clamp(deltaAngle,-MAX_ANG_DIFF,MAX_ANG_DIFF);
    }
    sumDeltaAngle-=storedDeltaAngle[deltaAngleIndex];
    sumDeltaAngle+=deltaAngle;
    storedDeltaAngle[deltaAngleIndex++]=deltaAngle;
    deltaAngleIndex%=storedDeltaAngle.length;
    deltaOverflow-=DELTA_UPDATE_TIME;
    float rotationAngle=sumDeltaAngle / maxStoredDeltaAngles;
    rotationAngle=Utils.clamp(rotationAngle,-MAX_ANG_DIFF,MAX_ANG_DIFF);
    float rotationPerSec=rotationAngle * (1000 / DELTA_UPDATE_TIME) / TWO_PI;
    drawnRPM=(int)(Math.abs(rotationPerSec * 60));
    rotate(rotationAngle);
  }
  return false;
}

Fixed version (ground truth):
@Override public boolean update(int delta,int mouseX,int mouseY,boolean keyPressed,int trackPosition){
  if (trackPosition > hitObject.getEndTime()) {
    hitResult();
    return true;
  }
  if (isSpinning && !(keyPressed || GameMod.RELAX.isActive()))   isSpinning=false;
  deltaOverflow+=delta;
  float angleDiff=0;
  if (GameMod.AUTO.isActive()) {
    angleDiff=delta * AUTO_MULTIPLIER;
    isSpinning=true;
  }
 else   if (GameMod.SPUN_OUT.isActive() || GameMod.AUTOPILOT.isActive()) {
    angleDiff=delta * SPUN_OUT_MULTIPLIER;
    isSpinning=true;
  }
 else {
    float angle=(float)Math.atan2(mouseY - (height / 2),mouseX - (width / 2));
    if (!isSpinning && (keyPressed || GameMod.RELAX.isActive())) {
      lastAngle=angle;
      isSpinning=true;
      return false;
    }
    angleDiff=angle - lastAngle;
    if (Math.abs(angleDiff) > 0.01f)     lastAngle=angle;
 else     angleDiff=0;
  }
  if (angleDiff < -Math.PI)   angleDiff+=TWO_PI;
 else   if (angleDiff > Math.PI)   angleDiff-=TWO_PI;
  if (isSpinning)   deltaAngleOverflow+=angleDiff;
  while (deltaOverflow >= DELTA_UPDATE_TIME) {
    float deltaAngle=0;
    if (isSpinning) {
      deltaAngle=deltaAngleOverflow * DELTA_UPDATE_TIME / deltaOverflow;
      deltaAngleOverflow-=deltaAngle;
      deltaAngle=Utils.clamp(deltaAngle,-MAX_ANG_DIFF,MAX_ANG_DIFF);
    }
    sumDeltaAngle-=storedDeltaAngle[deltaAngleIndex];
    sumDeltaAngle+=deltaAngle;
    storedDeltaAngle[deltaAngleIndex++]=deltaAngle;
    deltaAngleIndex%=storedDeltaAngle.length;
    deltaOverflow-=DELTA_UPDATE_TIME;
    float rotationAngle=sumDeltaAngle / maxStoredDeltaAngles;
    rotationAngle=Utils.clamp(rotationAngle,-MAX_ANG_DIFF,MAX_ANG_DIFF);
    float rotationPerSec=rotationAngle * (1000 / DELTA_UPDATE_TIME) / TWO_PI;
    drawnRPM=(int)(Math.abs(rotationPerSec * 60));
    rotate(rotationAngle);
  }
  return false;
}