Null, exceptions and stack traces

This page is still being written.

What it will cover

• null: a variable that points at nothing; NullPointerException with a runnable example (expectExit 1) and its helpful message
• Null checks, early returns, @Nullable in the Paper API (Bukkit.getPlayerExact returns null when offline)
• Exceptions: try/catch/finally, throw, checked vs unchecked, multi-catch, try-with-resources
• Reading a stack trace top to bottom; Caused by; finding your own class and line number (annotated x-console)
• Common exceptions table: NullPointerException, NumberFormatException, ArrayIndexOutOfBounds, ClassCastException, IllegalArgumentException, IllegalStateException, ConcurrentModificationException
• Validating player input (Integer.parseInt with catch)
• Link to Error Doctor and debugging chapter