Fix int range widget minimum value

The int range widget so far assigned NULL to the minimum value when allowNull was activated. This made it impossible to enter the minimum value into a range widget.

This also fixes some signals which in case of a NULL value would emit a slightly-below-minimum value for double and int spinboxes.

Fix #18297

src/gui/editorwidgets/qgsrangewidgetwrapper.cpp

@@ -128,24 +128,27 @@ void QgsRangeWidgetWrapper::initWidget( QWidget *editor )
       mDoubleSpinBox->setSuffix( config( QStringLiteral( "Suffix" ) ).toString() );
 
     connect( mDoubleSpinBox, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ),
-    this, [ = ]( double value ) { emit valueChanged( value ); } );
+    this, [ = ]( double ) { emitValueChanged(); } );
   }
   else if ( mIntSpinBox )
   {
     QgsSpinBox *qgsWidget = qobject_cast<QgsSpinBox *>( mIntSpinBox );
     if ( qgsWidget )
       qgsWidget->setShowClearButton( allowNull );
+    int minval = min.toInt();
     if ( allowNull )
     {
-      int minval = min.toInt();
       int stepval = step.toInt();
       minval -= stepval;
       mIntSpinBox->setValue( minval );
       mIntSpinBox->setSpecialValueText( QgsApplication::nullRepresentation() );
     }
-    setupIntEditor( min, max, step, mIntSpinBox, this );
+    setupIntEditor( minval, max, step, mIntSpinBox, this );
     if ( config( QStringLiteral( "Suffix" ) ).isValid() )
       mIntSpinBox->setSuffix( config( QStringLiteral( "Suffix" ) ).toString() );
+
+    connect( mIntSpinBox, static_cast < void ( QSpinBox::* )( int ) > ( &QSpinBox::valueChanged ),
+    this, [ = ]( int ) { emitValueChanged(); } );
   }
   else
   {