I've just downloaded a fresh copy of angular.min.js, and I'm getting a 404 on angular.min.js.map, which I'm not including in my code:
<link rel="stylesheet" type="text/css" href="css/bootstrap.min.css" />
GET http://angular.dev/js/angular.min.js.map 404 (Not Found)
Open the angular.min.js file in a text editor. There will be a comment at the end like this:
Delete that and the error will disappear.
A map file facilitates regenerating the minified version of a script based on changes to a non-minified version. Since you won't be making changes to angular.js, you don't need the map.