Ignore event_offset in cnt when no events exist.

[jaeilepp]

cf. mailing list.

Adding a test would require adding a small file which I don't have.

[codecov-io]

Codecov Report

Merging #4520 into master will increase coverage by 0.15%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #4520      +/-   ##
==========================================
+ Coverage   83.44%   83.59%   +0.15%     
==========================================
  Files         349      349              
  Lines       65212    65216       +4     
  Branches    10083    10085       +2     
==========================================
+ Hits        54414    54517     +103     
+ Misses       7945     7843     -102     
- Partials     2853     2856       +3

[agramfort]

Would it be possible to have a test?

Can you update what's new?

[agramfort]

@jaeilepp did you try on the problematic file ? how do you know it works?

[jaeilepp]

Yeah, I have the problematic file. It's 2GB. The event_offset field in the file header was a negative value. Rest of the header seems okay.

[agramfort]

ok let's say it works then...

[agramfort]

thx @jaeilepp