From 1ebdfa149a27768d6ead01dfed7feae1cdd1ca94 Mon Sep 17 00:00:00 2001
From: "J.D. Purcell" <jdpurcell@gmail.com>
Date: Sun, 13 Oct 2019 14:21:15 -0400
Subject: [PATCH] Fix NullReferenceException in ToolManager.IsAvailable and
 remove unnecessary try/catch.

---
 BizHawk.Client.EmuHawk/ToolAttribute.cs     | 11 ++++++-----
 BizHawk.Client.EmuHawk/tools/ToolManager.cs |  8 ++------
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/BizHawk.Client.EmuHawk/ToolAttribute.cs b/BizHawk.Client.EmuHawk/ToolAttribute.cs
index 721fa0cf48..53a2f837da 100644
--- a/BizHawk.Client.EmuHawk/ToolAttribute.cs
+++ b/BizHawk.Client.EmuHawk/ToolAttribute.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace BizHawk.Client.EmuHawk
 {
@@ -9,14 +10,14 @@ namespace BizHawk.Client.EmuHawk
 		public ToolAttribute(bool released, string[] supportedSystems, string[] unsupportedCores = null)
 		{
 			Released = released;
-			SupportedSystems = supportedSystems;
-            UnsupportedCores = unsupportedCores;
+			SupportedSystems = supportedSystems ?? Enumerable.Empty<string>();
+			UnsupportedCores = unsupportedCores ?? Enumerable.Empty<string>();
 		}
 
-		public bool Released { get; private set; }
+		public bool Released { get; }
 
-		public IEnumerable<string> SupportedSystems { get; private set; }
+		public IEnumerable<string> SupportedSystems { get; }
 
-        public IEnumerable<string> UnsupportedCores { get; private set; }
+		public IEnumerable<string> UnsupportedCores { get; }
 	}
 }
diff --git a/BizHawk.Client.EmuHawk/tools/ToolManager.cs b/BizHawk.Client.EmuHawk/tools/ToolManager.cs
index fef10a6b4b..e8bc2338ae 100644
--- a/BizHawk.Client.EmuHawk/tools/ToolManager.cs
+++ b/BizHawk.Client.EmuHawk/tools/ToolManager.cs
@@ -752,12 +752,8 @@ namespace BizHawk.Client.EmuHawk
 				return false;
 			}
 
-			ToolAttribute attr;
-			try
-			{
-				attr = tool.GetCustomAttributes(false).OfType<ToolAttribute>().Single();
-			}
-			catch (InvalidOperationException e)
+			ToolAttribute attr = tool.GetCustomAttributes(false).OfType<ToolAttribute>().SingleOrDefault();
+			if (attr == null)
 			{
 				return true; // no ToolAttribute on given type -> assumed all supported
 			}