This fixed my problem also. I was initially using 4.4.X. Wondering, though, why I didn't see some kind of error. Is the place to look for error messages the Javascript console, or is there somewhere else also?
I'm trying to follow the first tutorial. I don't understand why I don't see anything unless I uncomment out the resize() (which is not in the tutorial), and even when I do, the background color is not as specified in the Application object. Any pointers would be appreciated.
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Hello World</title>
</head>
<body>
<script src="pixi/pixi.min.js"></script>
<script type="text/javascript">
//Create a Pixi Application
let app = new PIXI.Application({