I see this all the time, too, since purchasing the trail runner upgrade upon resurrection. I'm pretty sure it's being triggered by trail runners generated for sulfur:
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ERROR in
action number 1
of Draw Event
for object o_bonus_ore_trail_runner:
local variable spr(100546) not set before reading it.
at gml_Object_o_bonus_ore_trail_runner_Draw_0
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gml_Object_o_bonus_ore_trail_runner_Draw_0 (line -1)