Use "backslashreplace" for encoding errors

[ryan-shaw]

When encountering bytes that are not of the expected encoding the file read throws an exception and stops reading completely.

This commit will replace the bytes with an escaped sequence.

More info: https://docs.python.org/3/library/io.html#io.TextIOWrapper

[bgreenlee]

Good catch. Would it be possible to add a test case for this?

[ryan-shaw]

Will do