Error: Expected reject to be called with Error, got [object Undefined]

Hi, I am currently developing a CustomUI App. It runs fine for admin users.
However, I just created a normal User without any admin permissions, and whenever I load the app, I get the prompt to “Allow access” for the App, followed by a second such prompt, and then the App never loads and this error is thrown in the Chrome console:

Error: Expected reject to be called with Error, got [object Undefined]
    at t.reject (https://jira-frontend-static.prod.public.atl-paas.net/assets-brotli/async-forge-ui-iframe-full-page.fd6977f46e491475a3b7.8.js:839:769)
    at https://jira-frontend-static.prod.public.atl-paas.net/assets-brotli/async-forge-ui-iframe-full-page.fd6977f46e491475a3b7.8.js:839:209

Error: Expected reject to be called with Error, got [object Undefined]
    at hn.error (https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:19406)
    at Object.<anonymous> (https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:27179)
    at JSON.parse (<anonymous>)
    at o (https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:27038)
    at jn (https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:27191)
    at Tn.u.on (https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:31851)
    at Tn (https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:31988)
    at https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:37974
    at n.try (https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:10458)
    at https://forge.cdn.prod.atlassian-dev.net/global-bridge.js:1:37771

I am stuck and I do not know how to debug this. The error seems to be happening at the entry point for the app, where I call the following:

const context = await view.getContext()
const history = await view.createHistory()
const myself = await invoke('getMyself')
const flows = await invoke('getFlows')
const canvas = await invoke('getCanvas')
resolver.define('getFlows', async (req) => {
    console.log('getFlows');
    const savedFlows = await storage.get('savedFlows');
    const projectFlows = Object.keys(req.payload).length ? savedFlows?.filter(flows => flows.projectKey === req.payload) : savedFlows
    return projectFlows || []
});
resolver.define('getCanvas', async (req) => {
    console.log('getCanvas');
    const canvas = await storage.get('canvas');
    return canvas || {}
});
resolver.define('getMyself', async (req) => {
    console.log('getMyself');
    const response = await api.asUser().requestJira(route`/rest/api/2/myself`)
    return response.json();
});

It looks like the issue isn’t permissions related, as I deployed the App into production, and now the Admins face this issue, while the normal user doesn’t. Any help is appreciated.

Were you able to figure this out? I went back to the hello-world app and narrowed it down to simply having “permissions > external > fetch > backend” in my manifest, even though the hello-world app has no fetch calls anywhere.