remove this.error()

it’s been deprecated for long enough

lib/context.js

@@ -62,20 +62,6 @@ var proto = module.exports = {
     throw err;
   },
 
-  /**
-   * Alias for .throw() for backwards compatibility.
-   * Do not use - will be removed in the future.
-   *
-   * @param {String|Number} msg
-   * @param {Number} status
-   * @api private
-   */
-
-  error: function(msg, status){
-    console.warn('ctx.error is deprecated, use ctx.throw');
-    this.throw(msg, status);
-  },
-
   /**
    * Default error handling.
    *