Facing issue with angular ui-router 1.0.5 and angular 1.6.5 in IE11 browser

Question

ui-router is causing an issue in the IE11 browser, Everything is working fine in chrome, firefox, and even IE10.

getting following error in the browser console.

SCRIPT5022: [$injector:modulerr] Failed to instantiate module TestApp due to:
TypeError: Object.keys: argument is not an Object
   at _extend (https://example.com/scripts/vendor.09a8eb90.js:100012:9)
   at Anonymous function

I'm pasting the ui-router code here where exactly causing an issue.

function _extend(toObj) {
    for (var i = 1; i < arguments.length; i++) {
        var obj = arguments[i];
        if (!obj)
            continue;
        var keys = Object.keys(obj);
        for (var j = 0; j < keys.length; j++) {
            toObj[keys[j]] = obj[keys[j]];
        }
    }
    return toObj;
}

https://cdnjs.cloudflare.com/ajax/libs/angular-ui-router/1.0.3/angular-ui-router.js

Any guesses of why this happening would be greatly appreciated.