DiagnosticDelegate: Fix leaking QVBoxLayout

Change-Id: I523c2c13b2b7f2b2eebc00781b6a2e18a74f8c17
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

plugins/clangstaticanalyzer/clangstaticanalyzerdiagnosticview.cpp

@@ -234,12 +234,13 @@ QWidget *ClangStaticAnalyzerDiagnosticDelegate::createDetailsWidget(const QFont
                                                                     QWidget *parent) const
 {
     QWidget *widget = new QWidget(parent);
-    QVBoxLayout *layout = new QVBoxLayout;
 
     const Diagnostic diagnostic = index.data(Qt::UserRole).value<Diagnostic>();
     if (!diagnostic.isValid())
         return widget;
 
+    QVBoxLayout *layout = new QVBoxLayout;
+
     // Add summary label
     QLabel *summaryLineLabel = createSummaryLabel(diagnostic);
     connect(summaryLineLabel, &QLabel::linkActivated,