Unexcepted null value in Path._onMouseMove method.

[warrenwyf]

This issue is caused by Leaflet.draw plugin, I set "L_PREFER_CANVAS =true;" in my page and draw polylines on Map, then exception thrown at this line:

if (this._map._animatingZoom) { return; }

At this time this._map is null.

[mourner]

Fixed blindly in master, please check if it works.

[warrenwyf]

Yes, it works.