Always validate that parameters contain expected types and values within safe boundaries, not just null/undefined checks. Optional parameters can receive unexpected types (like event objects), and numeric parameters need boundary validation to prevent invalid operations.

For optional parameters, verify the actual type matches expectations:

// Bad: assumes i is either number or undefined
deleteSession(i?: number) {
  const index = i ?? get().currentSessionIndex; // fails when i is an event object
}

// Good: validate the parameter type
deleteSession(i?: number) {
  const index = (typeof i === 'number') ? i : get().currentSessionIndex;
}

For numeric operations, use boundary checks to prevent invalid results:

// Bad: can create negative indices when historyMessageCount is 0
session.messages.slice(n - config.historyMessageCount)

// Good: ensure non-negative starting index
session.messages.slice(Math.max(0, n - config.historyMessageCount))

This prevents runtime errors from undefined values and invalid array operations.

Add Repository

Private Repository