How to use the webiny-model.ModelError function in webiny-model

const value = await this.getValidationValue();
        const valueValidation = !Attribute.isEmptyValue(value);

        if (valueValidation && this.hasMultipleEntityClasses()) {
            if (!this.options.classIdAttribute) {
                throw new ModelError(
                    `Entity attribute "${
                        this.name
                    }" accepts multiple Entity classes but does not have "classIdAttribute" option defined.`,
                    ModelError.INVALID_ATTRIBUTE
                );
            }

            let classIdAttribute = this.getClassIdAttribute();
            if (!classIdAttribute) {
                throw new ModelError(
                    `Entity attribute "${
                        this.name
                    }" accepts multiple Entity classes but classId attribute is missing.`,
                    ModelError.INVALID_ATTRIBUTE
                );
            }

            // We only do class validation if list of classes has been provided. Otherwise, we don't do the check.
            // This is because in certain cases, a list of classes cannot be defined, and in other words, any
            // class of entity can be assigned. One example is the File entity, which has an "ref" attribute, which
            // can actually link to any type of entity.
            if (!this.canAcceptAnyEntityClass()) {
                if (!this.getEntityClass()) {
                    const heldValue = await classIdAttribute.getValue();
                    if (!(typeof heldValue === "string")) {
                        throw new EntityError(

async validate() {
        // If attribute is dirty, has validators or loading is in progress, wait until loaded.
        if (this.value.isDirty() || this.hasValidators() || this.value.isLoading()) {
            await this.value.load();
        }

        if (!this.value.isLoaded()) {
            return;
        }

        const value = await this.getValidationValue();
        const valueValidation = !Attribute.isEmptyValue(value);

        if (valueValidation && this.hasMultipleEntityClasses()) {
            if (!this.options.classIdAttribute) {
                throw new ModelError(
                    `Entity attribute "${
                        this.name
                    }" accepts multiple Entity classes but does not have "classIdAttribute" option defined.`,
                    ModelError.INVALID_ATTRIBUTE
                );
            }

            let classIdAttribute = this.getClassIdAttribute();
            if (!classIdAttribute) {
                throw new ModelError(
                    `Entity attribute "${
                        this.name
                    }" accepts multiple Entity classes but classId attribute is missing.`,
                    ModelError.INVALID_ATTRIBUTE
                );
            }