salix/print/core/mixins/prop-validator.js

const Vue = require('vue');
const validator = {
    created() {
        const props = this.$options.props;
        const invalidProps = [];

        for (const prop in props) {
            const isObject = typeof props[prop] === 'object';
            const isRequired = props[prop].required;
            const isNotDefined = this[prop] === undefined;

            if (isObject && isRequired && isNotDefined)
                invalidProps.push(prop);
        }

        if (invalidProps.length > 0) {
            const required = invalidProps.join(', ');

            throw new Error(`Required properties not found [${required}]`);
        }
    },
    props: ['isPreview', 'access_token']
};

Vue.mixin(validator);