Promise rejected after context unloaded: An unexpected error occurred

Add-ons Development
#1

My code is here.

I am trying to load this extension as a temporary extension from about:debugging, and reloading the extension causes the error Promise rejected after context unloaded: An unexpected error occurred from background.js to appear in the browser console. Nothing in the extension console. When this occurs, the extension is broken and slows down Firefox. Happens on latest FIrefox release and Developer Edition.

How to fix the extension?

This is the error:

Promise rejected after context unloaded: An unexpected error occurred
background.js:1
    setValue moz-extension://1e81cbeb-a409-4cbe-94ac-2d401760dc88/background.js:1
can't access dead object IndexedDB.jsm:99
    method resource://gre/modules/IndexedDB.jsm:99
    set resource://gre/modules/ExtensionStorageIDB.jsm:243
    AsyncFunctionNext self-hosted:807
#2

It seems FirstPartyService.PSL_UPDATE_INTERVAL was undefined due to the order of static definitions.

export class FirstPartyService {
  private static INSTANCE = new FirstPartyService();
  private static PSL_STORAGE_KEY = "dns.publicSuffixList";
  private static PSL_UPDATE_INTERVAL = 1000 * 60 * 60 * 24; // 1 day

to

export class FirstPartyService {
  private static PSL_STORAGE_KEY = "dns.publicSuffixList";
  private static PSL_UPDATE_INTERVAL = 1000 * 60 * 60 * 24; // 1 day

  // This must be at the end of static definitions.
  private static INSTANCE = new FirstPartyService();

Is it that accessing too often browser.storage.* causes that errors?

#3

Oops, PSL_STORAGE_KEY was also undefined, so that would have been causing rejections, since storage key was empty.

I do not do so many this type of mistakes with plain JavaScript, but I need to understand what the TypeScript compiler does.