Previous commit introduced a new race condition. It was possible that…

… thread A could invoke `TaskQueue.Dispose()` and set `_isDisposed = 1`, which would then allow thread B to finish work setting `_held = false` but without releasing the semaphore, and then thread A would attempt `_semaphore.Wait()` entering a deadlock.

lib/PuppeteerSharp/Helpers/TaskQueue.cs

@@ -52,11 +52,8 @@ internal async Task<T> Enqueue<T>(Func<Task<T>> taskGenerator)
             }
             finally
             {
+                TryRelease(_semaphore);
                 _held.Value = false;
-                if (_disposed == 0)
-                {
-                    _semaphore.Release();
-                }
             }
         }
 
@@ -70,11 +67,21 @@ internal async Task Enqueue(Func<Task> taskGenerator)
             }
             finally
             {
+                TryRelease(_semaphore);
                 _held.Value = false;
-                if (_disposed == 0)
-                {
-                    _semaphore.Release();
-                }
+            }
+        }
+
+        private void TryRelease(SemaphoreSlim semaphore)
+        {
+            try
+            {
+                semaphore.Release();
+            }
+            catch (ObjectDisposedException)
+            {
+                // If semaphore has already been disposed, then Release() will fail
+                // but we can safely ignore it
             }
         }
     }