I have some old PDF files that include hex strings with whitespace (\n). I am pretty sure this is legal PDF though it seems to be very rare. The FileParser class does not ignore this whitespace while building the hex string and as a result later attempts to convert the data to bytes fail.
I fixed it in my own copy of 0.1.1 by changing line 286 of FileParser.cs from
if (!IsWhitespace(c)) buffer.Append((char)c);