[ZPack] Possible broken linedef in E3M0

[NovaRain]

When playing with the latest GZdoom dev build (gzdoom-x64-g4.13pre-122-g76c8b6da5.7z), I can't walk past this line, nor can it trigger the new area reveal:

I tried to check the line in SLADE's map editor, but couldn't see it:

Then I checked the TEXTMAP and found the supposed linedef (by searching vertex numbers):

linedef // 9690
{
v1 = 4549;
v2 = 5156;
special = 226;
arg0 = 1;
arg2 = 12;
twosided = true;
dontdraw = true;
playercross = true;
}

Comparing to the line 5026 (the selected line 1) it's missing sidefront and sideback properties. So I copied them from 5026, and now the line works.

linedef // 9690
{
v1 = 4549;
v2 = 5156;
sidefront = 10047;
sideback = 10048;
special = 226;
arg0 = 1;
arg2 = 12;
twosided = true;
dontdraw = true;
playercross = true;
}

But I'm not sure if it's a correct solution or just me got lucky not crashing the whole map, since I have zero experience on Doom mapping.

On an unrelated note, is the boss spider supposed to hurt the player badly on death? Seems to me it's kinda punishing to players not keeping enough health/armor or not trying to rush to exit quickly.