Files with 0 bytes sizes are not being sent

[SleepySquash]

Summary

Files with 0 bytes sizes have two issues with uploading. We should either fix those, or display a proper message to the end user.

Steps to reproduce

1. Drag-n-drop a 0 bytes empty text file.
2. Notice the error that file exceeds 15 MiB.

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1. Attach the files with 0 bytes to the message field via "File" picker menu.
2. Try sending the file.
3. Notice the waiting for upload for ~30 seconds.
4. Notice the error.

This was tested under Web platform. Should also investigate the native ones.

What is the current bug behavior?

Unexpected error happens.

What is the expected correct behavior?

Either no error happen, or an appropriate message is displayed.