[gjs: 2/3] value: Take null boxed pointer into account when calling signal handler

[Philip Chimento <pchimento src gnome org>]

commit 718dd8c1c4ae45fdce6da42dd4ae7be42480b0d3
Author: Philip Chimento <philip chimento gmail com>
Date:   Thu Aug 1 22:45:33 2019 -0700

    value: Take null boxed pointer into account when calling signal handler
    
    This was a regression from commit 91434941, where the error handling
    around GError boxed values was improved. Previously null pointers would
    sneak through and turn into null JS::Values, but now they were treated
    as errors and prevented the signal handler from being called.
    
    The solution is to check for a null pointer coming from C before doing
    anything else with it, and return a null JS::Value if so.
    
    Closes: GNOME/gjs#262

 gi/value.cpp                              |  7 +++++++
 installed-tests/js/testEverythingBasic.js | 25 +++++++++++++++++++++++++
 2 files changed, 32 insertions(+)
---
diff --git a/gi/value.cpp b/gi/value.cpp
index a375c34a..8d567a7f 100644
--- a/gi/value.cpp
+++ b/gi/value.cpp
@@ -849,6 +849,13 @@ gjs_value_from_g_value_internal(JSContext             *context,
         else
             gboxed = g_value_get_variant(gvalue);
 
+        if (!gboxed) {
+            gjs_debug_marshal(GJS_DEBUG_GCLOSURE,
+                              "Converting null boxed pointer to JS::Value");
+            value_p.setNull();
+            return true;
+        }
+
         /* special case GError */
         if (g_type_is_a(gtype, G_TYPE_ERROR)) {
             obj = ErrorInstance::object_for_c_ptr(context,
diff --git a/installed-tests/js/testEverythingBasic.js b/installed-tests/js/testEverythingBasic.js
index 77bee144..5746c466 100644
--- a/installed-tests/js/testEverythingBasic.js
+++ b/installed-tests/js/testEverythingBasic.js
@@ -719,6 +719,31 @@ describe('Life, the Universe and Everything', function () {
         });
     });
 
+    describe('GError signal', function () {
+        let o;
+        beforeEach(function () {
+            o = new Regress.TestObj();
+        });
+
+        it('with GError set', function (done) {
+            o.connect('sig-with-gerror', (obj, e) => {
+                expect(e instanceof Gio.IOErrorEnum).toBeTruthy();
+                expect(e.domain).toEqual(Gio.io_error_quark());
+                expect(e.code).toEqual(Gio.IOErrorEnum.FAILED);
+                done();
+            });
+            o.emit_sig_with_error();
+        }).pend('https://gitlab.gnome.org/GNOME/gobject-introspection/merge_requests/169');
+
+        it('with no GError set', function (done) {
+            o.connect('sig-with-gerror', (obj, e) => {
+                expect(e).toBeNull();
+                done();
+            });
+            o.emit_sig_with_null_error();
+        }).pend('https://gitlab.gnome.org/GNOME/gobject-introspection/merge_requests/169');
+    });
+
     // Calling matches() on an unpaired error used to JSUnit.assert:
     // https://bugzilla.gnome.org/show_bug.cgi?id=689482
     it('bug 689482', function () {