Stacks check for invalid amounts (#91656)

## About The Pull Request
Alleviates #91603

As in it does not fix it because i have not been able to reproduce it.
It now checks for invalid values and defaults to `amount`(which is 1)
during `Initialize()` and not null so we don't have to pass the number
`1` when creating a single sheet.
 
A stack trace is thrown for <= 0 sheet amounts so we can debug & fix
stuff

## Changelog
🆑
code: stacks error on invalid amounts, removed manual passing of number
`1` when creating a single stack in many cases
/🆑

code/modules/mapfluff/ruins/lavalandruin_code/elephantgraveyard.dm

@@ -77,11 +77,11 @@
 
 /turf/closed/mineral/strong/wasteland/drop_ores()
 	if(prob(10))
-		new /obj/item/stack/ore/iron(src, 1)
-		new /obj/item/stack/ore/glass(src, 1)
+		new /obj/item/stack/ore/iron(src)
+		new /obj/item/stack/ore/glass(src)
 		new /obj/effect/decal/remains/human(src, 1)
 	else
-		new /obj/item/stack/sheet/bone(src, 1)
+		new /obj/item/stack/sheet/bone(src)
 
 //***Oil well puddles.
 /obj/structure/sink/oil_well //You're not going to enjoy bathing in this...