Add NULL checks at tile::pull()

[palemieux]

4536793000378368

[aous72]

Thank you for putting this. I think this is a bug somewhere else in the code. I need to get to the bottom of it.

[palemieux]

Thank you for putting this. I think this is a bug somewhere else in the code. I need to get to the bottom of it.

pull_line() can return NULL, so this needs to be checked, right?

[aous72]

I am a bit blurry here. I think it is being called on a non-existing comp_num; if I recall correctly, this should not happen.

[aous72]

I tracked it down. The commit is messy because endline spaces are removed.
I did not use your PR.
I only added

      ui32 comp_width = recon_comp_rects[comp_num].siz.w;
      if (comp_width == 0)
        return true; // nothing to pull, but not an error

Remove the lines that repeat this line.

[aous72]

This was solved another way.
Thank you Pierre.