Flaky test modify_fantasy_variable: bad icon operation

[github-actions]

Flaky tests were detected in this test run. This means that there was a failure that was cleared when the tests were simply restarted.
Failures:

modify_fantasy_variable: [09:37:43] Runtime in ,: bad icon operation
proc name: New (/icon/New)
src: /icon (/icon)
call stack:
/icon (/icon): New('sound/effects/pop_expl.ogg', null, null, null, null)
Plushie Lizard (/datum/greyscale_config/plush_lizard): Generate("#b6939b#000000", null)
Greyscale (/datum/controller/subsystem/processing/greyscale): GetColoredIconByType("/datum/greyscale_config/plush_...", "#b6939b#000000")
the lizard plushie (/obj/item/toy/plush/lizard_plushie): update greyscale()
the lizard plushie (/obj/item/toy/plush/lizard_plushie): update greyscale()
the lizard plushie (/obj/item/toy/plush/lizard_plushie): set greyscale("#b6939b#000000", null, null, null, null)
the lizard plushie (/obj/item/toy/plush/lizard_plushie): set greyscale(/list (/list), null, null, null, null)
the lizard plushie (/obj/item/toy/plush/lizard_plushie): Initialize(0)
Atoms (/datum/controller/subsystem/atoms): InitAtom(the lizard plushie (/obj/item/toy/plush/lizard_plushie), 0, /list (/list))
the lizard plushie (/obj/item/toy/plush/lizard_plushie): New(0)
/datum/unit_test/modify_fantas... (/datum/unit_test/modify_fantasy_variable): allocate(/obj/item/toy/plush/lizard_plu... (/obj/item/toy/plush/lizard_plushie))
/datum/unit_test/modify_fantas... (/datum/unit_test/modify_fantasy_variable): Run()
RunUnitTest(/datum/unit_test/modify_fantas... (/datum/unit_test/modify_fantasy_variable), /list (/list))
RunUnitTests()
/datum/callback (/datum/callback): InvokeAsync() at OUTDATED_TEST:1