Fix error in uploadContent() when file is empty under Node.js (#2155)
Fix error in uploadContent() when file is empty under Node.js (#2155)

* Fix error in uploadContent() when file is empty under Node.js

* Make type safe check work

* Make comment actually make sense
matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk