fix description about crypto.randomBytes

remove outdated examples about crypto.randomBytes to make it clear

fix outdated examples about crypto.randomBytes to make it clear

The code shows that it throws on a lack of entropy, but the note below says that it does not.
Remove outdated `try/catch`statements in sync examples about crypto.randomBytes to make it clear

The code shows that it throws on a lack of entropy, but the note below says that it does not.
Remove outdated try/catchstatements in sync examples about crypto.randomBytes to make it clear

The code shows that it throws on a lack of entropy, but the note below says that it does not.
Remove outdated `try/catch`statements in sync examples about crypto.randomBytes to make it clear

The code shows that it throws on a lack of entropy, but the note below says that it does not.
Remove outdated `try/catch`statements in sync examples about crypto.randomBytes to make it clear

The code shows that it throws on a lack of entropy, but the note below says that it does not.
Remove outdated try/catchstatements in sync examples about crypto.randomBytes to make it clear.
In addition, use `const` instead of `var` for constant variable.