tweaks to the error message and update deps

[watilde]

• Use stdout when stderr is empty
• update vnu-jar version

[watilde]

Somehow this error was still existing. I updated the value of -Xss.

Message:
    StackOverflowError while evaluating HTML schema.
The checker requires a java thread stack size of at least 512k.
Consider invoking java with the -Xss option. For example:
  java -Xss512k -jar ~/vnu.jar FILE.html

[ghost]

Keep it up2date 👍