Seems like on chrome when cancel is hit in the file chooser, the 'changed' event is fired and startUpload() was being called. We need to check to see if the upload file is blank and - if so - just return immediately out of the function
use better API
make local variable
Merge pull request #129 from edx/fix/cdodge/cancel-asset-upload-crash

[STUD-256] Seems like on chrome when cancel is hit in the file chooser, the 'change...