[gjs: 5/16] js: Fix various error handling mistakes

[Philip Chimento <pchimento src gnome org>]

commit 8a29daa5f01c48a32a94392c9a60189f470c2199
Author: Philip Chimento <philip chimento gmail com>
Date:   Sun Oct 28 16:48:51 2018 -0400

    js: Fix various error handling mistakes
    
    These weren't caught by the compiler warnings, just by inspection as I
    was making the other edits.

 gi/enumeration.cpp       |  5 ++---
 gi/function.cpp          |  5 +----
 gi/fundamental.cpp       |  6 +++++-
 gi/interface.cpp         |  5 ++---
 gi/union.cpp             |  9 ++++++---
 modules/cairo-region.cpp | 14 ++++++++++----
 6 files changed, 26 insertions(+), 18 deletions(-)
---
diff --git a/gi/enumeration.cpp b/gi/enumeration.cpp
index ade2295b..2a1a2f95 100644
--- a/gi/enumeration.cpp
+++ b/gi/enumeration.cpp
@@ -109,9 +109,8 @@ gjs_define_enum_values(JSContext       *context,
     if (!gtype_obj)
         return false;
 
-    JS_DefineProperty(context, in_object, "$gtype", gtype_obj, JSPROP_PERMANENT);
-
-    return true;
+    return JS_DefineProperty(context, in_object, "$gtype", gtype_obj,
+                             JSPROP_PERMANENT);
 }
 
 bool
diff --git a/gi/function.cpp b/gi/function.cpp
index 49f14eef..ebe74142 100644
--- a/gi/function.cpp
+++ b/gi/function.cpp
@@ -501,10 +501,7 @@ gjs_callback_trampoline_new(JSContext       *context,
     GjsCallbackTrampoline *trampoline;
     int n_args, i;
 
-    if (function.isNull()) {
-        return NULL;
-    }
-
+    g_assert(function.isObject());
     g_assert(JS_TypeOfValue(context, function) == JSTYPE_FUNCTION);
 
     trampoline = g_slice_new(GjsCallbackTrampoline);
diff --git a/gi/fundamental.cpp b/gi/fundamental.cpp
index c661d0d0..01b949f6 100644
--- a/gi/fundamental.cpp
+++ b/gi/fundamental.cpp
@@ -577,8 +577,12 @@ gjs_lookup_fundamental_prototype(JSContext    *context,
                                           &constructor, &ignored))
             return nullptr;
     } else {
-        if (G_UNLIKELY (!value.isObject()))
+        if (G_UNLIKELY(!value.isObject())) {
+            gjs_throw(context,
+                      "Fundamental constructor was not an object, it was a %s",
+                      JS::InformalValueTypeName(value));
             return NULL;
+        }
 
         constructor = &value.toObject();
     }
diff --git a/gi/interface.cpp b/gi/interface.cpp
index 266689bf..e8235c0b 100644
--- a/gi/interface.cpp
+++ b/gi/interface.cpp
@@ -256,9 +256,8 @@ gjs_define_interface_class(JSContext              *context,
     if (!gtype_obj)
         return false;
 
-    JS_DefineProperty(context, constructor, "$gtype", gtype_obj, JSPROP_PERMANENT);
-
-    return true;
+    return JS_DefineProperty(context, constructor, "$gtype", gtype_obj,
+                             JSPROP_PERMANENT);
 }
 
 bool
diff --git a/gi/union.cpp b/gi/union.cpp
index 13f1a80e..d120ce2a 100644
--- a/gi/union.cpp
+++ b/gi/union.cpp
@@ -150,6 +150,10 @@ union_new(JSContext       *context,
              * discard.
              */
             if (rval.isNull()) {
+                gjs_throw(context,
+                          "Unable to construct union type %s as its"
+                          "constructor function returned NULL",
+                          g_base_info_get_name(info));
                 return NULL;
             } else {
                 JS::RootedObject rval_obj(context, &rval.toObject());
@@ -355,9 +359,8 @@ gjs_define_union_class(JSContext       *context,
     if (!gtype_obj)
         return false;
 
-    JS_DefineProperty(context, constructor, "$gtype", gtype_obj, JSPROP_PERMANENT);
-
-    return true;
+    return JS_DefineProperty(context, constructor, "$gtype", gtype_obj,
+                             JSPROP_PERMANENT);
 }
 
 JSObject*
diff --git a/modules/cairo-region.cpp b/modules/cairo-region.cpp
index f30453b3..aaf65154 100644
--- a/modules/cairo-region.cpp
+++ b/modules/cairo-region.cpp
@@ -153,19 +153,25 @@ make_rectangle(JSContext *context,
                cairo_rectangle_int_t *rect)
 {
     JS::RootedObject rect_obj(context, JS_NewPlainObject(context));
+    if (!rect_obj)
+        return nullptr;
     JS::RootedValue val(context);
 
     val = JS::Int32Value(rect->x);
-    JS_SetProperty(context, rect_obj, "x", val);
+    if (!JS_SetProperty(context, rect_obj, "x", val))
+        return nullptr;
 
     val = JS::Int32Value(rect->y);
-    JS_SetProperty(context, rect_obj, "y", val);
+    if (!JS_SetProperty(context, rect_obj, "y", val))
+        return nullptr;
 
     val = JS::Int32Value(rect->width);
-    JS_SetProperty(context, rect_obj, "width", val);
+    if (!JS_SetProperty(context, rect_obj, "width", val))
+        return nullptr;
 
     val = JS::Int32Value(rect->height);
-    JS_SetProperty(context, rect_obj, "height", val);
+    if (!JS_SetProperty(context, rect_obj, "height", val))
+        return nullptr;
 
     return rect_obj;
 }