old_contents: export class LaconaError extends Error {
    constructor(message) {
      super()
      this.message = message
      this.stack = (new Error()).stack;
      this.name = this.constructor.name;
    }
  }
  
new_contents: export function LaconaError(message){
      this.message = message;
  }
  
  LaconaError.prototype = new Error();
  
subject: Update error for new babel 6 impl