Fix kaddressarbiter crash (ryubing/ryujinx!235)

See merge request ryubing/ryujinx!235

.gitignore

@@ -100,6 +100,7 @@ DocProject/Help/html
 
 # Click-Once directory
 publish/
+RyubingMaintainerTools/
 
 # Publish Web Output
 *.Publish.xml

src/Ryujinx.HLE/HOS/Kernel/Threading/KAddressArbiter.cs

@@ -529,7 +529,13 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
             // The value is decremented if the number of threads waiting is less
             // or equal to the Count of threads to be signaled, or Count is zero
             // or negative. It is incremented if there are no threads waiting.
-            int waitingCount = _arbiterThreads[address].Count;
+            int waitingCount = 0;
+            
+            if (_arbiterThreads.TryGetValue(address, out List<KThread> threads))
+            {
+                waitingCount = threads.Count;
+            }
+            
 
             if (waitingCount > 0)
             {