do not crash on unicode decode errors

[gilfree]

Some programs e.g. pip in versions 21.X emit non strictly output unicode.

This means that running pip install something in pyxtermjs crashes pyxtermjs due to a unicode error, if there is a long progress bar:

To reproduce, inside pyxtermjs do:

python3 -mvenv venv
source venv/bin/activate
pip install -U pip==21.*
pip install torch

pyxtermjs crashes with:

line 41, in read_and_forward_pty_output
    output = os.read(app.config["fd"], max_read_bytes).decode()
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe2 in position 4094: unexpected end of data

After this change - the above works.

[cs01]

Thanks!

[gilfree]

Thanks for merging.

Will it be possible to release a fixed version to pypi? May I help with that somehow?

[cs01]

Sure! I just published to v0.5.0.1