fix: map layer update error

frontend/src/components/MapComponent.vue

@@ -152,8 +152,11 @@ export default {
         };
 
         const updateSamplesLayer = () => {
+            if (map.value.getLayer('samples-layer')){
                 map.value.removeLayer('samples-layer');
+            }
             
+            if(props.idlist.length){
                 map.value.addLayer({
                         'id': 'samples-layer',
                         'source': 'samples',
@@ -173,7 +176,7 @@ export default {
                         },
                         filter: ["match", ["get", "internal_id"], props.idlist, true, false]
                     });
-
+            }
         };
 
         onMounted(() => {