A number of codecs raise bare UnicodeError, rather than Unicode{Decode,Encode}Error. Example:

  File "/home/antoine/miniconda3/envs/pyarrow/lib/python3.7/encodings/utf_16.py", line 67, in _buffer_decode
    raise UnicodeError("UTF-16 stream does not start with BOM")

A more complete list can be found here:
https://gist.github.com/pitrou/60594b28d8e47edcdb97d9b15d5f9866

This looks like an easy task. Shall I create a PR?

Hi,

IMO this can be mark as an easy issue.

@thatiparthy please, go ahead

UnicodeEncodeError and UnicodeDecodeError are used to report un(en|de)codedable ranges in the source object, so it wouldn't make sense to use them for errors that have nothing to do with problems in the source object. Their constructor requires 5 arguments (encoding, object, start, end, reason), not just a simple message: e.g. UnicodeEncodeError("utf-8", "foo", 17, 23, "bad string").

But for reporting e.g. missing BOMs at the start it would be useful to use (0,  0) as the offending range.

@utk You could have taken some other easy issue from https://bugs.python.org/issue?status=1&@sort=-activity&@columns=id%2Cactivity%2Ctitle%2Ccreator%2Cstatus&@dispname=Easy%20issues&@startwith=0&@group=priority&keywords=6&@action=search&@filter=&@pagesize=50 instead of copy pasting my work.

@thatiparthy These were the most logical changes, standard error messages, which were already there in the existing code, I just edited them as mentioned here. What part of your "work" do you think i copied?
Sent this PR to get familiar to the process mostly, i will close it if you feel insecure. No need to be rude.
thanks.