Error when using loadJSON should catch error and not stop the process if there is an errorCallback

Most appropriate sub-area of p5.js?

• Accessibility (Web Accessibility)
• Build tools and processes
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Friendly error system
• Image
• IO (Input/Output)
• Localization
• Math
• Unit Testing
• Typography
• Utilities
• WebGL
• Other (specify if possible)

Details about the bug:

• p5.js version: 1.3.1
• Web browser and version: Firefox 88.0.1
• Operating System: Linux
• Steps to reproduce this:

let meta = { 
  // default value
  metadata: {}
};

function preload() {
  const uri = 'unknown.json';
  
  function onLoad(data) {
    meta.metadata = data;
  }
  
  function onError(error) {
    console.log(error);
  }
  
  loadJSON(uri, onLoad, onError);
}

function setup() {
  createcanvas(windowWidth, windowHeight);
  fill(255);
  rect(0, 0, 250, 250);
}

I am trying to fetch a file. This file can be present or not, therefore I have default data already set.

Since I provide an onError callback, It explicitly means that I wish to handle the error myself. I expect the error to be catched and passed to the onError callback, without stopping the current process.

However, here, the error is passed to onError but is not catched, so it propagates and stop everything from working.

Start at the loadJSON entry point described in the reproduction and trace how its error callback handles a missing unknown.json file. Confirm that providing onError prevents the error from stopping the process, while the callback still receives the error and the default metadata remains usable.