Improve "Type error" when looking up a property of null or undefined

Before:
    MenuItem.qml:98: TypeError: Type error
After:
    MenuItem.qml:101: TypeError: Cannot read property 'height' of null

The wording matches the similar error messages in qv4runtime.cpp.

Change-Id: I3d9b3506195fe8e17e78117f2f51aba2adbc0564
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Laurent Montel <laurent.montel@kdab.com>
 

1 files changed, 7 insertions, 2 deletions

diff --git a/src/qml/jsruntime/qv4lookup.cpp b/src/qml/jsruntime/qv4lookup.cpp
index f8999342d1..6b8fb509a8 100644
--- a/src/qml/jsruntime/qv4lookup.cpp
+++ b/src/qml/jsruntime/qv4lookup.cpp
@@ -77,8 +77,13 @@ ReturnedValue Lookup::resolvePrimitiveGetter(ExecutionEngine *engine, const Valu
     primitiveLookup.type = object.type();
     switch (primitiveLookup.type) {
     case Value::Undefined_Type:
-    case Value::Null_Type:
-        return engine->throwTypeError();
+    case Value::Null_Type: {
+        Scope scope(engine);
+        ScopedString name(scope, engine->currentStackFrame->v4Function->compilationUnit->runtimeStrings[nameIndex]);
+        const QString message = QStringLiteral("Cannot read property '%1' of %2").arg(name->toQString())
+            .arg(QLatin1String(primitiveLookup.type == Value::Undefined_Type ? "undefined" : "null"));
+        return engine->throwTypeError(message);
+    }
     case Value::Boolean_Type:
         primitiveLookup.proto = engine->booleanPrototype()->d();
         break;