Firefox 47, Permission denied to access property "type"

I see error logs in my sentry pointing to hammer. Firefox 47 (always) on windows xp, 7, 10 and ubuntu This is in production, minified, I’ve forgotten to enable sourcemaps, but it i traceable to library code:

Permission denied to access property "type"

// /assets/app/js/app.js in [96]</</<.handler at line 3:6296
!function t(e,n,i){function r(s,a){if(!n[s]){if(!e[s]){var u="function"==typeof require&&require;if(!a&&u)return u(s,!0);if(o)return o(s,!0) {snip}
u.removeChild(this),y.call(t)}}:function(t){setTimeout(s(y,t,1),0)}),e.exports={set:f,clear:d}},{"./_cof":17,"./_ctx":20,"./_dom-create":23, {snip}
{snip} own",Zt="mousemove mouseup";c(F,T,{handler:function(t){var e=Yt[t.type];e&Pt&&0===t.button&&(this.pressed=!0),e&At&&1!==t.which&&(e=Mt),this {snip}
}}(),f=h?this:document.createElement("a"),d=new r(l.search?l.search.substring(1):null);return d._url_object=f,Object.defineProperties(f,{hre {snip}

this traces to node_modules/hammerjs/hammer.js:804 at var eventType = MOUSE_INPUT_MAP[ev.type];:

inherit(MouseInput, Input, {
    /**
     * handle mouse events
     * @param {Object} ev
     */
    handler: function MEhandler(ev) {
        var eventType = MOUSE_INPUT_MAP[ev.type];

        // on start we want to have the left mouse button down
        if (eventType & INPUT_START && ev.button === 0) {
            this.pressed = true;
        }

        if (eventType & INPUT_MOVE && ev.which !== 1) {
            eventType = INPUT_END;
        }

        // mouse must be down
        if (!this.pressed) {
            return;
        }

        if (eventType & INPUT_END) {
            this.pressed = false;
        }

        this.callback(this.manager, eventType, {
            pointers: [ev],
            changedPointers: [ev],
            pointerType: INPUT_TYPE_MOUSE,
            srcEvent: ev
        });
    }
});

UPD

After enabling sourcemaps:

[ksykulev]

Getting the same issue’s popping up in our Rollbar Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:47.0) Gecko/20100101 Firefox/47.0

[combs]

We are seeing this too on washingtonian.com. We are not using Google Closure. There are iframes for our ads but they are not involved in our Hammer code.