fix datepicker

static/js/app.js

@@ -12,7 +12,7 @@ const coinTop50 = {
       const elems = document.querySelectorAll('.datepicker');
       this.datepicker = M.Datepicker.init(elems, {onClose:()=>{
         this.date = this.datepicker.date.toISOString().slice(0,10)
-      }});
+      }})[0];
     },
     watch:{
       date(newDate,oldDate){