saveGif() crashes when duration <= 0 (empty frame list path)

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• p5.strands
• WebGL
• DevOps, Build process, Unit testing
• Internationalization (i18n)
• Friendly Errors
• Other (specify if possible)

p5.js version

main

Web browser and version

Chrome (latest stable)

Operating system

Windows 11 (should be OS-independent)

Steps to reproduce this

Steps:

• Create any sketch.
• Call saveGif('test', 0) (or negative duration) in setup() or from a key handler.
• Check console.

snippet:

function setup() {
  createCanvas(100, 100);
  background(220);
  circle(50, 50, 30);

  // Repro: zero duration
  saveGif('test', 0);
  // also repros with negatives, e.g. saveGif('test', -1);
}

Console error:

TypeError: Cannot read properties of undefined (reading 'length')

Expected behavior
saveGif() should reject invalid duration early (e.g. duration must be > 0)
or gracefully handle zero captured frames without crashing.

Actual behavior
duration <= 0 leads to zero captured frames, then palette generation path assumes frames[0] exists and crashes.

Start at the saveGif() entry point and trace the zero-duration path through captured frames and palette generation, especially the frames[0] access mentioned in the report. Reproduce with saveGif('test', 0) and a negative duration in setup(); done means invalid durations no longer produce the reported TypeError and the chosen behavior is covered by the relevant test.