Unable to distinguish valid stream end from broken stream

[wstrzalka]

Hi

I had recently run into an issue while importing large pbf file.
The problem was broken input stream and I ended up importing only half of the expected data that got unnoticed.
It's impossible to find out whether the import completed successfully and the EOFException is legit (basically that will be the case only while reading headersize in FileBlockHead.readHead) or whether the stream is broken in the middle of processing and it can not read the data to be expected down the line (any other place).

Either exception shall be thrown in such a case or another callback method in Sink introduced so Sink::complete() is called upon success and Sink:failure() upon error?