ui.app.parent getter throws TypeError when accessed from ui.View

[blahah]

Description

When accessing ui.app.parent from within a ui.View, the getter throws a TypeError before the parent reference can be used. This happens even when the view has been properly opened and the parent exists.

Environment

• Pear Runtime: v2.2.6
• pear-electron: ^1.7.25
• Platform: macOS darwin-arm64

Steps to Reproduce

1. Create a parent app that opens a ui.View:

import ui from 'pear-electron'

const view = new ui.View('./child.html', { /* options */ })
view.on('message', (type, data) => {
  console.log('Message from child:', type, data)
})
await view.open()
await view.send('init', { someData: true })

2. In the child view (child.html), try to access ui.app.parent:

import ui from 'pear-electron'

// This throws TypeError
const parent = ui.app.parent

Error

Uncaught TypeError: The "listener" argument must be of type function. Received undefined
    at checkListener (events:140:11)
    at Readable.once (events:634:3)
    at get parent (pear-electron/lib/index.js:163:24)

The error originates from the getter implementation itself, not from subsequent usage.

Workaround

Wrap the access in a try-catch:

let parent = null
try {
  parent = ui.app.parent
} catch (err) {
  console.warn('Failed to access ui.app.parent:', err)
}

if (parent) {
  parent.on('message', handleMessage)
  await parent.send('some-message', { data })
}

Expected Behavior

ui.app.parent should return the parent reference (or null if no parent exists) without throwing an error.

Additional Context

The view does work correctly after applying the workaround - messages can be sent and received between parent and child. The issue is specifically in the getter's internal implementation.

[blahah]

Root Cause Analysis

I traced through the source code and found the bug:

In gui/ipc.js:70 - receiveFrom takes only ONE argument:

receiveFrom (fn) {
  electron.ipcRenderer.on('send', fn)
  return () => electron.ipcRenderer.removeListener('send', fn)
}

But in api.js:86 - the Parent class constructor passes TWO arguments:

class Parent extends EventEmitter {
  constructor (id) {
    super()
    this.id = id
    ipc.receiveFrom(id, (...args) => {   // <-- Bug: passing id as first arg
      this.emit('message', ...args)
    })
  }

So fn receives id (not a function), and the actual listener callback is ignored. Then electron.ipcRenderer.on('send', fn) throws because fn (the id) isn't a function.

Compare to GuiCtrl#rxtx() at api.js:221 which calls it correctly with just the listener:

#rxtx () {
  this.#listener = (e, ...args) => this.emit('message', ...args)
  this.#unlisten = ipc.receiveFrom(this.#listener)  // <-- Correct: just the listener
}

The fix would be to change api.js:86 to match the expected signature:

ipc.receiveFrom((...args) => {
  this.emit('message', ...args)
})

Though it's unclear if receiveFrom was meant to also filter by id (in which case ipc.receiveFrom needs to be updated to accept an id parameter).

(credit to claude opus 4.5 for this analysis)

[AndreiRegiani]

@blahah did the patch work for you? if so, please create a PR, looks like you got the fix

[blahah]

@AndreiRegiani it does indeed - PR submitted.