Failed Preloads Without Error Callbacks Cause Permanent Sketch Hang

[Ady0333]

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

v1.11.12-rc.0

Web browser and version

Google Chrome 120.0.6099.216 (64-bit)

Operating system

Windows 11 (with WSL2, Ubuntu 22.04)

Steps to reproduce this

Steps:

1. Create a new p5.js sketch using the default global mode.
2. Add a preload() function that attempts to load a non-existent asset using a preload helper (e.g. loadImage) without providing an error callback.
3. Open the sketch in a browser and observe that it remains stuck on “Loading…” indefinitely and setup() / draw() never execute.

Snippet:

let img;

function preload() {
  // Intentionally invalid path to trigger a load failure
  img = loadImage('nonexistent-image.jpg');
}

function setup() {
  // This never runs
  createCanvas(400, 400);
  console.log('setup ran');
}

function draw() {
  // This never runs
  background(220);
  image(img, 0, 0);
}

Observed Behavior:

• Sketch displays “Loading…” forever

• No visible error in the sketch output

• setup() and draw() are never called

• Error is only visible in the browser console

Expected Behavior:

• Preload failures should not permanently block sketch execution

• setup() should run once all preload attempts (success or failure) complete

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[skyash-dev]

i don’t really see this as an issue. there’s already a clear friendly error in the console explaining what failed. since js is an interpreted language and preload() is explicitly meant to block until assets load, continuing to setup() after a preload failure wouldn’t make sense.

this looks like expected behavior rather than a bug. i think this can be closed.

ps: it also looks like preload() has been removed in the p5.js beta, so this likely won’t apply going forward.