Reset panel component while new one loads (#2693)

Signed-off-by: Denis Bunakalya <denis.bunakalya@xored.com>

packages/ui/src/components/PanelInstance.svelte

@@ -43,7 +43,7 @@
     direction: 'bottom'
   }
 
-  let component: AnySvelteComponent
+  let component: AnySvelteComponent | undefined
 
   let props: PanelProps | undefined
   function _close () {
@@ -53,6 +53,8 @@
   $: props = $panelstore.panel
 
   $: if (props !== undefined) {
+    component = undefined
+
     getResource(props.component).then((r) => {
       component = r
     })