[RUNTIME] Foam going over an "open space" tile on Icebox throws null.resolve

[MonkestationIssueBot]

Reporting client info: Client Information:
BYOND:515.1623
Key:dexee

Round ID:

3302

Testmerges:

• Behold, a Box!
• Fixes
• Bomber-type logs now mention if the bomber has the pacifist trait.
• [PORT] First aid analyzer rework and improvised medicine
• Various things
• Mining Skillchip

Reproduction:

[20:56:40] Runtime in code/game/turfs/open/openspace.dm, line 154: Cannot execute null.resolve().
proc name: CanAStarPass (/turf/open/openspace/CanAStarPass)
src: the open space (168,101,4) (/turf/open/openspace)
call stack:
the open space (168,101,4) (/turf/open/openspace): CanAStarPass(0, /datum/can_pass_info (/datum/can_pass_info))
the open space (168,101,4) (/turf/open/openspace): LinkBlockedWithAccess(the open space (168,101,4) (/turf/open/openspace), /datum/can_pass_info (/datum/can_pass_info))
the foam (/obj/effect/particle_effect/fluid/foam/short_life): spread(0.2)
Foam (/datum/controller/subsystem/fluids/foam): fire(1)
Foam (/datum/controller/subsystem/fluids/foam): fire(1)
Foam (/datum/controller/subsystem/fluids/foam): ignite(1)
Master (/datum/controller/master): RunQueue()
Master (/datum/controller/master): Loop(2)
Master (/datum/controller/master): StartProcessing(0)