QmlCompiler: When rejecting empty constants, don't crash afterwards

Fixes: QTBUG-119091
Change-Id: I1e24583aa998976c96bf3ddd6865f33cc4d5e94c
Reviewed-by: Olivier De Cannière <olivier.decanniere@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 8190f5bd68)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 6049b22c97)

src/qmlcompiler/qqmljscodegenerator.cpp

@@ -448,6 +448,7 @@ void QQmlJSCodeGenerator::generate_MoveConst(int constIndex, int destTemp)
         input = toNumericString(v4Value.doubleValue());
     } else {
         reject(u"unknown const type"_s);
+        return;
     }
     m_body += conversion(contained, changed, input) + u";\n"_s;
     generateOutputVariantConversion(contained);

tests/auto/qml/qmlcppcodegen/data/failures.qml

@@ -81,4 +81,6 @@ QtObject {
 
     readonly property int someNumber: 10
     function writeToReadonly() { someNumber = 20 }
+
+    property var silly: [,0]
 }