From ef4d97dfb49a52722d6a338be53a809641b6d2f0 Mon Sep 17 00:00:00 2001
From: John <vim2meta@tutanota.com>
Date: Sat, 3 Feb 2018 14:23:11 -0500
Subject: [PATCH] try catch precondition execution

---
 src/Discord.Net.Commands/CommandService.cs         | 14 ++++++++++++--
 .../Results/PreconditionResult.cs                  | 10 ++++++++--
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/Discord.Net.Commands/CommandService.cs b/src/Discord.Net.Commands/CommandService.cs
index 8e7dab898..8e3dce203 100644
--- a/src/Discord.Net.Commands/CommandService.cs
+++ b/src/Discord.Net.Commands/CommandService.cs
@@ -1,4 +1,4 @@
-using Discord.Commands.Builders;
+using Discord.Commands.Builders;
 using Discord.Logging;
 using System;
 using System.Collections.Concurrent;
@@ -287,7 +287,17 @@ namespace Discord.Commands
 
             foreach (var match in commands)
             {
-                preconditionResults[match] = await match.Command.CheckPreconditionsAsync(context, services).ConfigureAwait(false);
+                try
+                {
+                    preconditionResults[match] = await match.Command.CheckPreconditionsAsync(context, services).ConfigureAwait(false);
+                }
+                catch (Exception ex)
+                {
+                    if (_throwOnError)
+                        throw;
+
+                    return PreconditionResult.FromError(ex);
+                }
             }
 
             var successfulPreconditions = preconditionResults
diff --git a/src/Discord.Net.Commands/Results/PreconditionResult.cs b/src/Discord.Net.Commands/Results/PreconditionResult.cs
index ca65a373e..b8c96c754 100644
--- a/src/Discord.Net.Commands/Results/PreconditionResult.cs
+++ b/src/Discord.Net.Commands/Results/PreconditionResult.cs
@@ -1,17 +1,21 @@
-using System.Diagnostics;
+using System;
+using System.Diagnostics;
 
 namespace Discord.Commands
 {
     [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
     public class PreconditionResult : IResult
     {
+        public Exception Exception { get; }
+
         public CommandError? Error { get; }
         public string ErrorReason { get; }
 
         public bool IsSuccess => !Error.HasValue;
 
-        protected PreconditionResult(CommandError? error, string errorReason)
+        protected PreconditionResult(CommandError? error, string errorReason, Exception exception = null)
         {
+            Exception = exception;
             Error = error;
             ErrorReason = errorReason;
         }
@@ -20,6 +24,8 @@ namespace Discord.Commands
             => new PreconditionResult(null, null);
         public static PreconditionResult FromError(string reason)
             => new PreconditionResult(CommandError.UnmetPrecondition, reason);
+        public static PreconditionResult FromError(Exception ex)
+            => new PreconditionResult(CommandError.Exception, ex.Message, ex);
         public static PreconditionResult FromError(IResult result)
             => new PreconditionResult(result.Error, result.ErrorReason);