Steps to reproduce

1. Choose a file from the file dialog (using md-file component)
2. Open file dialog again, but this time press "escape" or "abort" (not picking a new file)

Which browser?

Using Chrome browser

Vue version 3.0 beta, Vue Material 1.0 Beta, Linux, Chrome

What is expected?

The old file name that was picked should remain in field

What is actually happening?

The old file name is replaced by [object Event] and an exception is thrown (Uncaught TypeError: Cannot read property 'constructor' of null)

Reproduction Link

https://vuematerial.io/components/file (choose any of the file components - same behavior)