[bug] onground condition not working for randomspawns

Summary

Adding the onground condition to randomspawns result in the mob never spawning.

Steps to reproduce

add the condition to a randomspawn, set the Chance to 1 and test

Current behavior

Mob never spawns on ground with a Chance set to 1

Intended correct behavior

Mob should spawn on ground with a Chance set to 1

EXAMPLE

ALIEN_SPAWN:
  Type: ALIEN_SPAWN
  Worlds: Survie
  Chance: 1
  Priority: 1
  Action: REPLACE
  Conditions:
  - outside true
  - onground true

Removing the condition result in the mob spawning as expected