Fix error when event.dataTransfer.files is empty
Fix error when event.dataTransfer.files is empty

Changelog-entry: Fix error when event.dataTransfer.files is empty
Change-type: patch

resin-io/etcher,resin-io/etcher,resin-io/herostratus,resin-io/herostratus,resin-io/etcher,resin-io/etcher,resin-io/resin-etcher,resin-io/resin-etcher,resin-io/etcher