So it tells me this in the log:
>>>
>>> There is an error in your config-file! Handle it!
>>> Here is what snakeyaml says:
>>>

mapping values are not allowed here
 in 'string', line 69, column 14:
            waves:
                 ^



And this is my config file:

Btw this is line 69 v
        waves:
            recurrent:
                zombiewave:
                    type: default
                    priority: 1
                    frequency: 1
                    monsters:
                        zombies: 10
                        zombie_pigmen: 2
            single:
                chickenswarm:
                    type: swarm
                    wave: 5
                    monster: chickens
                    amount: medium
                witherboss:
                    type: boss
                    wave: 10
                    monster: wither_skeleton
                    health: medium
                    abilities: lightning-aura, warp-to-player, fireballs
                    potions: wither, increase_damage:1
                    ability-interval: 5
                snowgolemboss:
                    type: boss
                    wave: 20
                    monster: snow_golem
                    health: psycho
                    abilities: root-target, arrows, pull-distant
                    potions: increase_damage:2
                    ability-interval: 5