I'm trying to write an AI Goal for an entity to move towards its target on each tick (with quite a few restrictions on when, which is why I need a new goal). It seemed to be working when I also added a WaterAvoidingRandomWalkingGoal, but I don't want the entity to move around randomly anymore, so I removed that. My code overrides the canUse function to determine whether or not it should start moving towards the target, and that ends with creating a path to the target, which always returns NULL, so nothing happens. Here's the relevant functions:

    public FloatingEyesGoal(EntityFloatingEyes e, double speed) {
        this.entity = e;
        this.random = e.getRandom();
        this.speed = speed;
        this.setFlags(EnumSet.of(Flag.LOOK, Flag.MOVE, Flag.TARGET));
        this.entity.getNavigation().setCanFloat(true);
    }

    @Override
    public boolean canUse() {
        LivingEntity target = this.entity.getTarget();
        if (target == null || !target.isAlive() || !isFacingTargetBack())
            return false;
            
        setTargetPos(target);
        this.path = this.entity.getNavigation().createPath(target, 0);
        // Logging this.path == null prints "true", and this.entity.getNavigation() == null prints "false"

        return this.path != null || isInRange(target);
    }

    @Override
    public boolean canContinueToUse() {
        LivingEntity target = this.entity.getTarget();
        if (target == null || !target.isAlive() || !isFacingTargetBack())
            return false;
        
        return !this.entity.getNavigation().isDone();
    }

    @Override
    public void start() {
        this.entity.getNavigation().moveTo(this.path, this.speed);
        this.entity.setAggressive(true);
        this.ticksToMove = 0;
    }

    @Override
    public void stop() {
        LivingEntity target = this.entity.getTarget();
        if (!EntityPredicates.NO_CREATIVE_OR_SPECTATOR.test(target)) {
            this.entity.setTarget(null);
        }
        this.entity.setAggressive(false);
        this.entity.getNavigation().stop();
        this.targetPosX = 0.0D;
        this.targetPosY = 0.0D;
        this.targetPosZ = 0.0D;
    }

    @Override
    public void tick() {
        // Look at target
        LivingEntity target = this.entity.getTarget();
        this.entity.getLookControl().setLookAt(target, 32.0F, 32.0F);
        
        setTargetPos(target);
        final double distance = this.entity.distanceToSqr(this.targetPosX, this.targetPosY, this.targetPosZ);

        this.ticksToMove--;
        LilSpooks.LOGGER.info(this.ticksToMove);
        if (this.ticksToMove <= 0
            && this.entity.getSensing().canSee(target)
            && target.distanceToSqr(this.targetPosX, this.targetPosY, this.targetPosZ) >= 1.0D) {
            this.ticksToMove = 5 + this.random.nextInt(8);

            // Add extra time if eyes can't move to hopefully wait enough to try again (1 second).
            this.path = this.entity.getNavigation().createPath(new BlockPos(this.targetPosX, this.targetPosY, this.targetPosZ), 0);
            // Logging this.path == null returns "true" here as well
            if (!this.entity.getNavigation().moveTo(this.path, this.speed)) {
                this.ticksToMove += 20;
            }
        }

        this.attackTick = Math.max(this.attackTick - 1, 0);
        this.attemptAttack(target, distance);
    }

    protected void setTargetPos(LivingEntity target) {
        this.targetPosX = target.getX();
        this.targetPosY = target.getBoundingBox().minY;
        this.targetPosZ = target.getZ();
    }

I have tried multiple ways of invoking createPath, I tried setting the moveControl of the entity with the goal to a new FlyingMovementController, and I've looked at how the createPath function works (though I can't figure out how to do a live debugging session, so I couldn't set a breakpoint at that code which would tell me exactly what causes it to be null). I tried my best to work through this for a few hours but I can't seem to figure it out. Any help is appreciated.

Edited June 19, 20214 yr by LoveAi
Title edit to show this issue has been solved

After looking through a ton of functions, I found the issue was that my entity was extending MonsterEntity, which extends MobEntity, which creates a GroundPathNavigator, which has a rules for canUpdatePath that include "this.mob.isOnGround()". My entity is a flying entity. Whoops. Solution was to simply override the createNavigation function, where I simply "return new FlyingPathNavigator(this, world);". Everything works fine now.