From dccb90f9f5ca0b14ebb2cb236315d0f1bf562f49 Mon Sep 17 00:00:00 2001
From: Brice <brice@xcit.org>
Date: Thu, 16 May 2019 15:42:08 +0200
Subject: [PATCH] Exception and fallback for WaitForBackgroundThread on WebGL

---
 .../Source/WaitForBackgroundThread.cs         | 24 ++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/UnityProject/Assets/Plugins/AsyncAwaitUtil/Source/WaitForBackgroundThread.cs b/UnityProject/Assets/Plugins/AsyncAwaitUtil/Source/WaitForBackgroundThread.cs
index a02a2d7..cadd66a 100644
--- a/UnityProject/Assets/Plugins/AsyncAwaitUtil/Source/WaitForBackgroundThread.cs
+++ b/UnityProject/Assets/Plugins/AsyncAwaitUtil/Source/WaitForBackgroundThread.cs
@@ -7,8 +7,30 @@
 
 public class WaitForBackgroundThread
 {
+    private readonly bool canFallbackToMainThread;
+    private readonly bool platformSupportsMultithread;
+
+    public WaitForBackgroundThread() : this(false) { }
+
+    public WaitForBackgroundThread(bool canFallbackToMainThread)
+    {
+        this.canFallbackToMainThread = canFallbackToMainThread;
+        this.platformSupportsMultithread = Application.platform != RuntimePlatform.WebGLPlayer;
+    }
+
     public ConfiguredTaskAwaitable.ConfiguredTaskAwaiter GetAwaiter()
     {
-        return Task.Run(() => {}).ConfigureAwait(false).GetAwaiter();
+        if (!platformSupportsMultithread && !canFallbackToMainThread)
+        {
+            throw new InvalidOperationException($"{Application.platform} does not support background threads.");
+        }
+
+        return Empty().ConfigureAwait(!platformSupportsMultithread).GetAwaiter();
+    }
+
+    private static async Task Empty()
+    {
+        // Task.Run does not run on WebGL, so we use this async method instead.
+        await Task.Yield();
     }
 }