Vue.js - Showing form errors when user clicks away from a component

I have a complex vue component called ExamEditor, which is itself composed of sub-components such as QuestionEditor, ExerciseEditor, and so on. It's tied to an exam object that contains nested arrays with questions, etc. Here's a sketch of the layout inside the exam editor:

 <QuestionEditor
    v-for="(question, index) in exam.questions"
    :id="'q-' + question.id"
    :key="'q-' + question.id"
    v-model="exam.questions[index]"
    :category-choices="exam.questionCategories"
    :errors="editorErrors.questionErrors[question.id]"
></QuestionEditor>
<!-- editors for exercises, etc. -->

Here's the full component.

I've been tackling the task of introducing data validation into this component to make sure only consistent "exams" can be saved.

Since there is some complex validation going on, I decided to roll my own function. My idea was to have an object like this:

   {
        globalErrors: [],
        questionErrors: {
            id:    [errMsg, ...],
            ...
        },
        exerciseErrors: { ... },
        questionCategoryErrors: { ... },
        exerciseCategoryErrors: { ... }
    }

that is, an object for each class of items in the editor and the errors for a given item are keyed by its id as a property in the object. I would then pass each array of errors (or undefined) as a prop to the sub-component editors for displaying the messages.

I then made a function that fills the object with the appropriate error strings. This is what the function looks like.

I put this function in a computed property to have it always in synch with the data, but here comes the issue: it always displays errors.

For example, as soon as I add a new question in my editor, errors will pop up telling me I didn't select a category, the question text is empty, and so on.

What I would like to do is have a way to display the errors at appropriate times. I think a good starting point would be to run the function when a sub-component is clicked away from. For example, I might add a question, forget to select a category for it (which is required), and when once I click "add question" to move on, the function is ran an displays the errors.

How can I achieve this?

Also (this could be opinion-based but I'm looking for some input): is this even the most appropriate way of displaying errors? How and when do you like to display errors in your forms? Keep in mind there are a lot of options in my component, the interface is very complex and borderline cluttered, so I want to keep it simple.

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