Why does this script crash Unity?

I can't figure it out. Sometimes itt crashes, sometimes it doesn't. It doesn't seem to relate to how many WordDisplays I have active, how the rate at which I spawn them, etc. I don't get any error messages on account of Unity freezing, so I can't figure it out.

 {
     private static string[] wordArray = {"floor","treaty","giant","lifestyle","reasonable","stream","shelf","medal","register","cereal","stage",
     "command","please", "separate",
     "intervention","rung","hover","fountain","cotton","attention","adoption",
     "leftovers","publish","inn","moment","eagle","mastermind", "sector","clinic", "trend", "jockey", "vegetable", "category", "upset", "rebel","progressive",
     "manner", "reporter", "zebra", "waterway",
     "wetworks", "window", "welfare", "all-star", "allegory", "beetle", "pungeant", "pageant", "peacock", "rubbish", "kerfuffle"};
 
     public static List<string> wordList = new List<string>();
     public static List<char> activeCharList = new List<char>();
     static WordDisplay[] wordDisplays;
 
     void Awake()
     {
         foreach (string word in wordArray)
         {
             wordList.Add(word);
         }
     }
 
     private void Update()
     {
         print(wordList.Count);
     }
 
     public static string GetRandomWord()
     {
         if (wordList.Count <= 3)
         {
             foreach (string word in wordArray)
             {
                 wordList.Add(word);
             }
         }
         
         wordDisplays = FindObjectsOfType<WordDisplay>(); //get all active word displays
         foreach (WordDisplay wordDisplay in wordDisplays) //then get all first characters of those wordsdisplays
         {
             activeCharList.Add(wordDisplay.textMeshPro.text[0]);
         }
 
         int randomIndex = Random.Range(0, wordList.Count);
         string randomWord = wordList[randomIndex];
 
         while (activeCharList.Contains(randomWord[0]))
         {
             randomIndex = Random.Range(0, wordList.Count);
             randomWord = wordList[randomIndex];
         }
 
         wordList.Remove(randomWord);
         return randomWord;
 
     }
 
 }