(C#) When I play this Method, Unity Just Shut Down So I cannot provide you to Error Code

First off, I gonna Discribe you to Script I'll trying to.

1. When the enemy's health reaches 0 in the game, call uiSelectUnit.Show().

   void Update()
    {
        if (!isLive)
            return;

        gameTime += Time.deltaTime;

        if (hasAllEnemiesSpawned && gameTime > 1.0f && enemies.Count == 0)
        {
            uiLevelUp.Show();
        }
    }

2.When Show() is Called, it activates the UI Window, pause the Game, and calls Next().

    public void Show()
    {
        Next();
        rect.localScale = Vector3.one;
        GameManager.instance.Stop();
    }

(+ There seem to be no issues up to step 2. There were no anomalies when tested with other scripts.)

3. Select three different indexes, assign data to the UnitCard/Draggable component of each index, and activate the cards.

 void Next()
    {
        foreach (UnitCard unitCard in unitCards)
        {
            unitCard.gameObject.SetActive(false);
        }

        int[] ran = new int[3];
        while (true)
        {
            ran[0] = Random.Range(0, unitDataItems.Length);
            ran[1] = Random.Range(0, unitDataItems.Length);
            ran[2] = Random.Range(0, unitDataItems.Length);

            if (ran[0] != ran[1] && ran[1] != ran[2] && ran[0] != ran[2])
                break;
        }

        for (int index = 0; index < ran.Length; index++)
        {
            UnitData ranUnitData = unitDataItems[ran[index]];
            UnitCard ranItem = unitCards[index];
            ranItem.GetComponent<UnitCard>().data = ranUnitData;
            ranItem.GetComponent<Draggable>().linkedUnitData = ranUnitData;
            ranItem.gameObject.SetActive(true);
        }
    }

    private UnitData[] LoadUnitDataFromResources()
    {
        Object[] loadedUnitData = Resources.LoadAll("Unit/Faction1", typeof(UnitData));
        UnitData[] unitDataItems = new UnitData[loadedUnitData.Length];

        for (int i = 0; i < loadedUnitData.Length; i++)
        {
            unitDataItems[i] = (UnitData)loadedUnitData[i];
        }

        return unitDataItems;
    }

After entering the steps as mentioned above and starting the game, when uiSelectUnit.Show() was called and Next was executed, Unity suddenly crashed and the game stopped... I'd like to tell you the error data, but I can't figure out the cause since it suddenly stopped... I'd really appreciate any help!

the data was managed as follows.
enter image description here
(The SelectUnit script is applied to the SelectUnit object, with Cards as its children connected to UnitCard. Data is set to None, as it is designed to connect automatically.)

If you need to full script to solve this Problem, Just tell me.

Display three randomly selected units, and allow the user to choose the desired unit.

The crash may be caused by the while loop in the function Next that never ends: the loop ends only if rand[0], rand[1] and rand[2] are different but, if there aren't many items in the array unitDataItems, it's possible that that condition never becomes true and the loop continues forever, thus crashing Unity.