Building to Web GL fails EVERY TIME. What am I doing wrong?

I'm trying to build a text adventure game that I wrote about 3 years ago to WebGL, and it simply will not build. If I build to WebAssembly it will run for about an hour before asm2wasm.exe crashes. If I build to asm.js then it will run for a long time, then simply disappear as though it is complete, but nothing at all is created in the build folder. Unity doesn't even give me the courtesy of spitting an error at me.

Naturally, I tried it on other machines (3 of them), but with the same results. I've also tried an older version of Unity. So far I've tried 2018.1.9, 2018.2.2, and 2018.2.5. The game runs flawlessly in the editor.

I thought maybe it was an issue with converting 12,000+ lines of C# to java (it's a long game), so I made a fresh "game" from scratch that simply contains 1 scene, 1 small PNG asset, and 1 script (below), but the results are the same.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class TextController : MonoBehaviour {
 
     private enum States {
                             Start, State1, State2, State3a, State3b, State3c, State3d, State4, State5, State6, State7
 
     }
     public Text text;
     private bool haveKey = false;
     private States state;
     private int keyTimer;
 
     // Use this for initialization
     void Start () {
         state = States.Start;
     }
     
     // Update is called once per frame
     void Update () {
         keyTimer -=1;
                             if (state == States.Start)      {stateStart(); }
                             if (state == States.State1)     {stateState1(); }
                             if (state == States.State2)     {stateState2(); }
                             if (state == States.State3a)    {stateState3a(); }
                             if (state == States.State3b)    {stateState3b(); }
                             if (state == States.State3c)    {stateState3c(); }
                             if (state == States.State3d)    {stateState3d(); }
                             if (state == States.State4)     {stateState4(); }
                             if (state == States.State5)     {stateState5(); }
                             if (state == States.State6)     {stateState6(); }
                             if (state == States.State7)     {stateState7(); }
         
     }
     #region States
     void stateStart(){
         text.text = "This is the starting state.\n\n\n\nPress Enter to begin.";
         if      (Input.GetKeyDown(KeyCode.KeypadEnter) && keyTimer <=0) {keyTimer = 20; state = States.State1; }
     }
     void stateState1(){
         text.text = "This is State 1.\n\n\n\nPress 1 to go to State 2.\nPress 2 to go to State 3.";
         if      (Input.GetKeyDown(KeyCode.Keypad1) && keyTimer <=0)     {keyTimer = 20; state = States.State2; }
         else if (Input.GetKeyDown(KeyCode.Keypad2) && keyTimer <=0)     {keyTimer = 20; state = States.State3a; }
     }
     void stateState2(){
         text.text = "This is State 2, which only connects to State 1.\n\n\n\nPress Enter to return to State 1.";
         if (Input.GetKeyDown(KeyCode.KeypadEnter) && keyTimer <=0){keyTimer = 20; state = States.State1; }
     }
     void stateState3a(){
         text.text = "This is State 3a. A key is required to move to State 4.\n\n\n\nPress 1 to go to State 4.\nPress 2 to collect the key.";
         if      (Input.GetKeyDown(KeyCode.Keypad1) && keyTimer <=0)     {keyTimer = 20; state = States.State3b; }
         else if (Input.GetKeyDown(KeyCode.Keypad2) && keyTimer <=0)     {keyTimer = 20; state = States.State3c; }
     }
     void stateState3b(){
         text.text = "This is State 3b, which exists to tell you that you cannot progress to State 4 without the key.\n\n\n\nPress Enter to return to State 3a.";
         if (Input.GetKeyDown(KeyCode.KeypadEnter) && keyTimer <=0){keyTimer = 20; state = States.State3a; }
     }
     void stateState3c(){
         text.text = "This is State 3c. You have collected the key.\n\n\n\nPress Enter to go to State 3d.";
         if (Input.GetKeyDown(KeyCode.KeypadEnter) && keyTimer <=0){keyTimer = 20; state = States.State3d; }
     }
     void stateState3d(){
         text.text = "This is State 3d. You have the key to State 4.\n\n\n\nPress Enter to go to State 4.";
         if (Input.GetKeyDown(KeyCode.KeypadEnter) && keyTimer <=0){keyTimer = 20; state = States.State4; }
     }
     void stateState4(){
         text.text = "This is the State 4.\n\n\n\nPress 1 to go to State 5.\nPress 2 to go to State 6.";
         if      (Input.GetKeyDown(KeyCode.Keypad1) && keyTimer <=0)     {keyTimer = 20; state = States.State5; }
         else if (Input.GetKeyDown(KeyCode.Keypad2) && keyTimer <=0)     {keyTimer = 20; state = States.State6; }
     }
     void stateState5(){
         text.text = "This is the State 5.\n\n\n\nPress 1 to go to State 6.\nPress 2 to return to State 4.";
         if      (Input.GetKeyDown(KeyCode.Keypad1) && keyTimer <=0)     {keyTimer = 20; state = States.State6; }
         else if (Input.GetKeyDown(KeyCode.Keypad2) && keyTimer <=0)     {keyTimer = 20; state = States.State4; }
     }
     void stateState6(){
         text.text = "This is State 6.\n\n\n\nPress Enter to go to State 7.";
         if (Input.GetKeyDown(KeyCode.KeypadEnter) && keyTimer <=0){keyTimer = 20; state = States.State7; }
     }
     void stateState7(){
         text.text = "This is the State 7. There are no more states\n\nGame Over.\n\n\n\nPress Enter to restart.";
         if (Input.GetKeyDown(KeyCode.KeypadEnter) && keyTimer <=0){keyTimer = 20; state = States.Start; }
     }
     #endregion
 }

What am I doing wrong?