I was testing the limits of custom soil and found an instance that can cause requiredticks to become negative,

Custom soil:
{ "type": "bonsaitrees3:soil", "tickModifier": 0.1, "soil": { "item": "minecraft:stone" }, "compatibleSoilTags": [ "grass" ], "display": { "block": "minecraft:stone" } }

For max vanilla efficiency lowest tickModifier you can use is 0.3, it will go negative with 0.1 and 0.2

Thanks for the report. Fix will be in the next release.