(This may be an upstream bug, but since upstream is apparently phasing it out, I'm not sure it's worth reporting there.)
Starting around February 5 and still going on as of a few minutes ago, visiting https://reviews.freebsd.org/D34099/new/ while logged in as myself results in a pop-up reading:
Unhandled Exception ("Exception")
Found unknown intradiff source line, expected a line beginning with "+", "-", or " " (space): \ No newline at end of file
Still happens, see https://reviews.freebsd.org/D35819/new/.
This problem often occurs if you are not using arc or rather uploading patch files you paste the diffs in the field. This is most likely due to the fact that there should be a blank line at the end of the patch. To distinguish between line feed and line seperator. And most probably while pasting the diff you removed the last line.
(In reply to Muhammad Moinur Rahman from comment #2)
Well, it's not me doing it, but you seem to be saying it's pilot error and the solution is to add "don't do that" to the documentation. Am I reading you correctly?