How to Implement Step Validation with react-hook-form without Using Zod Resolver?

I’m working on a multi-step form in React using react-hook-form, and I want to validate each step before allowing the user to proceed. I’m currently using the trigger method for validation, but I keep getting undefined when I try to call it. I don’t want to use a Zod resolver for validation.
Here is a snippet of my current implementation:

const form = useForm({
    defaultValues: {
        company: "",
        first_name: '',
        last_name: '',
        email: '',
        phone: '',
        password: '',
        password_confirmation: '',
        country: '',
        messenger: '',
        messenger_id: '',
        city: '',
        street_address: '',
        state: '',
        zip_code: ''
    },
});

const handleNextStep = async () => {
    console.log(`Current step: ${step}`);

    let isValid = false;

    // Validate based on current step
    if (step === 0) {
        isValid = await form.trigger(['email', 'phone', 'messenger', 'messenger_id']);
    } else if (step === 1) {
        isValid = await form.trigger(['company', 'first_name', 'last_name', 'street_address', 'city']);
    } else if (step === 3 || (step === 2 && !hasQuestions)) {
        isValid = await form.trigger(['password', 'password_confirmation']);
    }

    console.log(`Form valid: ${isValid}`);

    if (isValid) {
        if (step < totalSteps - 1) {
            setStep((prevStep) => prevStep + 1);
        } else {
            form.handleSubmit(onSubmit)();
        }
    } else {
        console.log(`Please complete the current step before proceeding.`);
    }
};

When I call form.trigger, it always returns undefined, preventing me from performing step validation. I need to ensure that users cannot proceed to the next step without completing the current one.

1.Why am I getting undefined when calling form.trigger?
2.What is the correct way to implement step validation in react-hook-form without using a resolver like Zod?
3.Are there any best practices or common pitfalls to avoid when validating multi-step forms with react-hook-form?

Thank you for your help!