Open Native Apps in WebApp

this is my first question here

I'm having a problem with my webapp. With chrome, the spotify and whatsapp floating icons open their respective apps, but in the webapp (a webview of the page) i get this error

the error

This is the code of the floating icons in the page

<div style=position:fixed;top:50%;margin-top:100px;right:20px;z-index:999999999999999999><a href="https://wa.me/541123609964"target=_blank><img src={(GBP_URLPICTUREFILES)}icowsflotante2.png></a></div>

it is my first web app. I'm a web designer, not a android programmer and this is getting difficult to me.