Fix PHP warning on GIS visualization when there is only one GIS column

```
Warning in ./libraries/classes/Controllers/Table/GisVisualizationController.php#174
 Undefined array key "labelColumn"

Backtrace

Routing.php#191: PhpMyAdmin\Controllers\Table\GisVisualizationController->__invoke(
,
array,
)
./../../../../index.php#43: PhpMyAdmin\Routing::callControllerForRoute(
,
string '/table/gis-visualization',
,
,
)
```
Structure:
- A table with only one GIS column

Signed-off-by: William Desportes <williamdes@wdes.fr>

1 files changed, 1 insertions, 1 deletions

diff --git a/libraries/classes/Controllers/Table/GisVisualizationController.php b/libraries/classes/Controllers/Table/GisVisualizationController.php
index c9ebeb29af..1f3021c952 100644
--- a/libraries/classes/Controllers/Table/GisVisualizationController.php
+++ b/libraries/classes/Controllers/Table/GisVisualizationController.php
@@ -171,7 +171,7 @@ final class GisVisualizationController extends AbstractController
                 'session_max_rows' => $rows,
                 'pos' => $pos,
                 'visualizationSettings[spatialColumn]' => $visualizationSettings['spatialColumn'],
-                'visualizationSettings[labelColumn]' => $visualizationSettings['labelColumn'],
+                'visualizationSettings[labelColumn]' => $visualizationSettings['labelColumn'] ?? null,
             ]
         ));