Fix call to representValue in identifydialog (refs #17175)

This should fix the problem of queries with WHERE (id = 'NULL') when the
string 'NULL' cannot be converted to integer / uuid, as seen with
relation reference widgets.

src/app/qgsidentifyresultsdialog.cpp

@@ -610,7 +610,7 @@ void QgsIdentifyResultsDialog::addFeature( QgsVectorLayer *vlayer, const QgsFeat
 
     QString value = fields.at( i ).displayString( attrs.at( i ) );
     const QgsEditorWidgetSetup setup = QgsGui::editorWidgetRegistry()->findBest( vlayer, fields.at( i ).name() );
-    QString value2 = representValue( vlayer, setup, fields.at( i ).name(), value );
+    QString value2 = representValue( vlayer, setup, fields.at( i ).name(), attrs.at( i ) );
 
     tblResults->setRowCount( j + 1 );