mapbox-gl/src/style-spec/error/validation_error.js

A WebGL interactive maps library

export default class ValidationError {
    constructor(key, value, message, identifier) {
        this.message = (key ? `${key}: ` : '') + message;
        if (identifier) this.identifier = identifier;

        if (value !== null && value !== undefined && value.__line__) {
            this.line = value.__line__;
        }
    }
}