I have searched google and stackoverflow, but could not find a solution for this issue. I am loading the map like this, in my vi
It seems you are generating a static map only in your view, in that case the loading of Bing Maps API (http://www.bing.com/api/maps/mapcontrol) and initializing map control (GetMap function) could be omitted.
The reason why you are getting the error:
TypeError: Cannot read property 'prototype' of null
is most likely due to missing map container declaration in your view
Example
var app = angular.module("myApp", []);
app.controller("bingMapsCtrl", function ($scope) {
$scope.Key = "As1l7HRtrpkXzjXozp3M2ufUTDvj16b2MHlpscQmHJEtxYFZWqwyccSx7I5XXEW_";
});