bugfix: #272 if the dialog is already open, close it (#294)

webui.dev/js/ExecutionDialog.js

@@ -75,6 +75,10 @@ export class ExecutionDialog {
       this.executionTick()
     }, 1000)
 
+    if (this.dlg.open) {
+      this.dlg.close()
+    }
+
     this.dlg.showModal()
   }