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/bitrunning/objects/loot_crate.dm

@@ -66,9 +66,11 @@
 
 /// Handles generating random numbers & calculating loot totals
 /obj/structure/closet/crate/secure/bitrunning/decrypted/proc/calculate_loot(reward_points, rewards_multiplier, ore_multiplier)
+	PRIVATE_PROC(TRUE)
+
 	var/base = rewards_multiplier + reward_points
 	var/random_sum = (rand() + 0.5) * base
-	return ROUND_UP(random_sum * ore_multiplier)
+	return max(ROUND_UP(random_sum * ore_multiplier), 1)
 
 /// Handles spawning completion loot. This tries to handle bad flat and assoc lists
 /obj/structure/closet/crate/secure/bitrunning/decrypted/proc/spawn_loot(list/completion_loot)