Google Apps Script DocumentApp annoyances

It took me a few hours to determine that there is a character limit to how much text you can save in a document. The limit is currently around 1.5 million characters according to my experiments.

This critical limit is poorly documented if at all! It is certainly not mentioned in the reference documentation when you look up e.g. body.setText() or appendText().

This is the entire documentation for setText() method. The documentation for appendText() is similar.