From ba7d33b4e46f9eafb4980f7a2b4865c5914e0fcc Mon Sep 17 00:00:00 2001
From: rec <44084068+recloser@users.noreply.github.com>
Date: Fri, 4 Jan 2019 15:05:03 +0100
Subject: [PATCH] Guard against null exception (#10162)

---
 lib/system/jssys.nim | 2 +-
 tests/js/test2.nim   | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/system/jssys.nim b/lib/system/jssys.nim
index 8be19e5b84..d7718e4f4e 100644
--- a/lib/system/jssys.nim
+++ b/lib/system/jssys.nim
@@ -46,7 +46,7 @@ proc nimCharToStr(x: char): string {.compilerproc.} =
   result[0] = x
 
 proc isNimException(): bool {.asmNoStackFrame.} =
-  asm "return `lastJSError`.m_type;"
+  asm "return `lastJSError` && `lastJSError`.m_type;"
 
 proc getCurrentException*(): ref Exception {.compilerRtl, benign.} =
   if isNimException(): result = cast[ref Exception](lastJSError)
diff --git a/tests/js/test2.nim b/tests/js/test2.nim
index 0bfb991397..9ecdbb35cf 100644
--- a/tests/js/test2.nim
+++ b/tests/js/test2.nim
@@ -9,6 +9,9 @@ js 3.14
 
 # This file tests the JavaScript generator
 
+doAssert getCurrentException() == nil
+doAssert getCurrentExceptionMsg() == ""
+
 #  #335
 proc foo() =
   var bar = "foo"