check read errors in fastqreader

[jchorl]

It turns out, if there is a read error while reading a fastq, fastp will loop infinitely.

Per cpp fread docs, it looks like the caller should check both feof and ferror. Because ferror wasn't checked, fastp went right back to readToBuf and looped infinitely.

The issue is really hard to reproduce because you need an unreliable filesystem. While complicated, thankfully I could rerun in our own environment and reliably reproduce, but not in a way I can easily post here.

Anyway, here are the logs I saw after fixing:

reading fastq failed: Transport endpoint is not connected
Failed reading: sg_9.fastq

And I saw:

Command exited with status: exit status: 1

So we do see the process actually exit instead of hang.