maybeMakeCommand(commandName, commandArgs) {
    if (this._environment === undefined) {
      throw new Error('Unable to make command without environment, you have to execute "run" method first.');
    }
    let CurrentCommand = lookupCommand(this._environment.commands, commandName, commandArgs, {
      project: this._environment.project,
      ui: this.ui,
    });

    /*
     * XXX Need to decide what to do here about showing errors. For
     * a non-CLI project the cache is local and probably should. For
     * a CLI project the cache is there, but not sure when we'll know
     * about all the errors, because there may be multiple projects.
     *   if (this.packageInfoCache.hasErrors()) {
     *     this.packageInfoCache.showErrors();
     *   }
     */
    let command = new CurrentCommand({
      ui: this.ui,
      commands: this._environment.commands,
      tasks: this._environment.tasks,
      project: this._environment.project,
      settings: this._environment.settings,
      testing: this.testing,
      cli: this,
    });

    return command;
  }
@private
@method maybeMakeCommand
@param commandName
@param commandArgs
@return {null|CurrentCommand}