using ionic, I want to write a tab switch, which can be regarded as secondary navigation. I got a component and wrote
< ion-header >

< ion-navbar >

<button ion-button icon-only menuToggle>
  <ion-icon name="menu"></ion-icon>
</button>

<ion-title>
  Page Title
</ion-title>

< / ion-navbar >

< / ion-header >
copy it directly on the Internet, and then you will see the error

it"s been a day. I don"t know what went wrong. What plug-ins are missing? Or what"s the problem? Ask God to take a look, thank you!