From 73cd2950eefcf037dd245fc7b9abecefa4276a7a Mon Sep 17 00:00:00 2001
From: Matthias Dittrich <matthi.d@gmail.com>
Date: Fri, 22 Feb 2019 20:18:04 +0100
Subject: [PATCH] Allow non F# union-types to be used as messages

fixes #20

Actually, I think this should have created problems for anyone not using F#-unions.
---
 src/debugger.fs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/debugger.fs b/src/debugger.fs
index fcfb6e8..0d38a7e 100644
--- a/src/debugger.fs
+++ b/src/debugger.fs
@@ -63,8 +63,12 @@ module Program =
     open FSharp.Reflection
 
     let inline private duName (x:'a) =
-        match FSharpValue.GetUnionFields(x, typeof<'a>) with
-        | case, _ -> case.Name
+        let t = typeof<'a>
+        if (isNull t?cases)
+        then "not-a-f#-union"
+        else
+            match FSharpValue.GetUnionFields(x, t) with
+            | case, _ -> case.Name
 
     let inline private getCase<'msg> (cmd: 'msg) : obj =
         createObj ["type" ==> duName cmd