[gjs/ewlsh/fix-callback-exit] Ensure exit when a closure fails after marshal.

[Evan Welsh <ewlsh src gnome org>]

commit 19fa52d545519d8fd5eea5df3175307abd0b145c
Author: Evan Welsh <contact evanwelsh com>
Date:   Thu Feb 11 17:41:09 2021 -0800

    Ensure exit when a closure fails after marshal.
    
    We didn't correctly check for an exit condition after mashalling,
    this caused a discrepancy with our other callback code and segfaults
    if System.exit was used in signal callbacks.
    
    Fixes #19

 gi/value.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
---
diff --git a/gi/value.cpp b/gi/value.cpp
index c9bb7f25..2dacf7fa 100644
--- a/gi/value.cpp
+++ b/gi/value.cpp
@@ -259,7 +259,15 @@ closure_marshal(GClosure        *closure,
     }
 
     JS::RootedValue rval(context);
-    mozilla::Unused << gjs_closure_invoke(closure, nullptr, argv, &rval, false);
+
+    if (!gjs_closure_invoke(closure, nullptr, argv, &rval, false)) {
+        // "Uncatchable" exception thrown, we have to exit. This
+        // matches the closure exit handling in function.cpp
+        uint8_t code;
+        if (gjs->should_exit(&code))
+            exit(code);
+    }
+
     // Any exception now pending, is handled when returning control to JS
 
     if (return_value != NULL) {