code: public static void sendErrorMail(String phase, Throwable e, String gMailUsername, String gMailPassword) {
          sendErrorMail(phase, null, e, gMailUsername, gMailPassword);
      }
docs: Sends a error message via gMail. This method requires a gMail account to send emails from. Get a new account <a href="https://accounts.google.com/SignUp?continue=https%3A%2F%2Fwww.google.com%2F%3Fgfe_rd%3Dcr%26ei%3D30aJWLDMDrP08Af3oLrwDg%26gws_rd%3Dssl&hl=en">here</a>
  
  @param phase         The phase in which the error occurred. This can be any string that helps you to identify the part of the code where the exception happened
  @param e             The exception that occurred
  @param gMailUsername The username of the gMail-account to use to send the mail from, including {@code {@literal @}gmail.com}
  @param gMailPassword The password of the gMail-account