void displayError(String errorMessage, { bool showUsage: false, CLIColor color: CLIColor.boldRed })

Source

void displayError(String errorMessage, {bool showUsage: false, CLIColor color: CLIColor.boldRed}) {
  outputSink.writeln("${colorSymbol(color)}$_ErrorDelimiter$errorMessage$defaultColorSymbol");
  if (showUsage) {
    outputSink.writeln("\n${options.usage}");
  }
}