Program: 156816
Project: 156816
Buggy source:
@Override protected void mouseClicked(int i,int j,int k){
  if (gate == null) {
    return;
  }
  super.mouseClicked(i,j,k);
  AdvancedSlot slot=getSlotAtLocation(i,j);
  if (slot instanceof TriggerSlot && container.hasTriggers()) {
    TriggerSlot triggerSlot=(TriggerSlot)slot;
    IStatement changed=null;
    if (triggerSlot.getStatement() == null) {
      if (k == 0) {
        changed=container.getFirstTrigger();
      }
 else {
        changed=container.getLastTrigger();
      }
    }
 else {
      Iterator<IStatement> it=container.getTriggerIterator(k != 0);
      for (; it.hasNext(); ) {
        IStatement trigger=it.next();
        if (!it.hasNext()) {
          changed=null;
          break;
        }
        if (trigger == triggerSlot.getStatement()) {
          changed=it.next();
          break;
        }
      }
    }
    if (changed == null) {
      container.setTrigger(triggerSlot.slot,null,true);
    }
 else {
      container.setTrigger(triggerSlot.slot,changed.getUniqueTag(),true);
    }
    for (    StatementParameterSlot p : triggerSlot.parameters) {
      container.setTriggerParameter(triggerSlot.slot,p.slot,null,true);
    }
  }
 else   if (slot instanceof ActionSlot) {
    ActionSlot actionSlot=(ActionSlot)slot;
    IStatement changed=null;
    if (actionSlot.getStatement() == null) {
      if (k == 0) {
        changed=container.getFirstAction();
      }
 else {
        changed=container.getLastAction();
      }
    }
 else {
      Iterator<IStatement> it=container.getActionIterator(k != 0);
      for (; it.hasNext(); ) {
        IStatement action=it.next();
        if (!it.hasNext()) {
          changed=null;
          break;
        }
        if (action == actionSlot.getStatement()) {
          changed=it.next();
          break;
        }
      }
    }
    if (changed == null) {
      container.setAction(actionSlot.slot,null,true);
    }
 else {
      container.setAction(actionSlot.slot,changed.getUniqueTag(),true);
    }
    for (    StatementParameterSlot p : actionSlot.parameters) {
      container.setActionParameter(actionSlot.slot,p.slot,null,true);
    }
  }
 else   if (slot instanceof StatementParameterSlot) {
    StatementParameterSlot paramSlot=(StatementParameterSlot)slot;
    StatementSlot statement=paramSlot.statementSlot;
    if (statement.isDefined() && statement.getStatement().maxParameters() != 0) {
      IStatementParameter param=paramSlot.getParameter();
      if (param == null) {
        param=statement.getStatement().createParameter(paramSlot.slot);
      }
      if (param != null) {
        param.onClick(gate,statement.getStatement(),mc.thePlayer.inventory.getItemStack(),k);
        paramSlot.setParameter(param,true);
      }
    }
  }
  container.markDirty();
}

Fixed version (ground truth):
@Override protected void mouseClicked(int i,int j,int k){
  if (gate == null) {
    return;
  }
  super.mouseClicked(i,j,k);
  AdvancedSlot slot=getSlotAtLocation(i,j);
  if (slot instanceof TriggerSlot && container.hasTriggers()) {
    TriggerSlot triggerSlot=(TriggerSlot)slot;
    IStatement changed=null;
    if (triggerSlot.getStatement() == null) {
      if (k == 0) {
        changed=container.getFirstTrigger();
      }
 else {
        changed=container.getLastTrigger();
      }
    }
 else {
      Iterator<IStatement> it=container.getTriggerIterator(k != 0);
      for (; it.hasNext(); ) {
        IStatement trigger=it.next();
        if (!it.hasNext()) {
          changed=null;
          break;
        }
        if (trigger == triggerSlot.getStatement()) {
          changed=it.next();
          break;
        }
      }
    }
    if (changed == null) {
      container.setTrigger(triggerSlot.slot,null,true);
    }
 else {
      container.setTrigger(triggerSlot.slot,changed.getUniqueTag(),true);
    }
    for (    StatementParameterSlot p : triggerSlot.parameters) {
      IStatementParameter parameter=null;
      if (changed != null && p.slot < changed.minParameters()) {
        parameter=changed.createParameter(p.slot);
      }
      container.setTriggerParameter(triggerSlot.slot,p.slot,parameter,true);
    }
  }
 else   if (slot instanceof ActionSlot) {
    ActionSlot actionSlot=(ActionSlot)slot;
    IStatement changed=null;
    if (actionSlot.getStatement() == null) {
      if (k == 0) {
        changed=container.getFirstAction();
      }
 else {
        changed=container.getLastAction();
      }
    }
 else {
      Iterator<IStatement> it=container.getActionIterator(k != 0);
      for (; it.hasNext(); ) {
        IStatement action=it.next();
        if (!it.hasNext()) {
          changed=null;
          break;
        }
        if (action == actionSlot.getStatement()) {
          changed=it.next();
          break;
        }
      }
    }
    if (changed == null) {
      container.setAction(actionSlot.slot,null,true);
    }
 else {
      container.setAction(actionSlot.slot,changed.getUniqueTag(),true);
    }
    for (    StatementParameterSlot p : actionSlot.parameters) {
      IStatementParameter parameter=null;
      if (changed != null && p.slot < changed.minParameters()) {
        parameter=changed.createParameter(p.slot);
      }
      container.setActionParameter(actionSlot.slot,p.slot,parameter,true);
    }
  }
 else   if (slot instanceof StatementParameterSlot) {
    StatementParameterSlot paramSlot=(StatementParameterSlot)slot;
    StatementSlot statement=paramSlot.statementSlot;
    if (statement.isDefined() && statement.getStatement().maxParameters() != 0) {
      IStatementParameter param=paramSlot.getParameter();
      if (param == null) {
        param=statement.getStatement().createParameter(paramSlot.slot);
      }
      if (param != null) {
        param.onClick(gate,statement.getStatement(),mc.thePlayer.inventory.getItemStack(),k);
        paramSlot.setParameter(param,true);
      }
    }
  }
  container.markDirty();
}