Steps to replicate the issue (include links if applicable):

• Install MobileFrontend and needed dependencies
• Make sure not to have VisualEditor installed
• Go to any page in the mobile version (e.g., useformat=mobile)
• Click the button to edit the page

What happens?:
The editor does not load, and the following error is logged in the console:

oojs.js:867 Uncaught TypeError: Cannot read properties of null (reading 'namespaces')
    at t.value (mobile.common.js:1:17590)
    at P (mobile.init.js:1:2338)
    at r.eval (mobile.init.js:1:3447)
    at r._matchRoute (mobile.common.js:1:15138)
    at r.eval (mobile.common.js:1:14727)
    at Array.reduce (<anonymous>)
    at r._checkRoute (mobile.common.js:1:14691)
    at OO.EventEmitter.emit (oojs.js:858:12)
    at eval (oojs-router.js:46:11)
    at OO.EventEmitter.emit (oojs.js:858:12)

What should have happened instead?:
The editor should load (without VE).

Software version (skip for WMF-hosted wikis like Wikipedia):
Everything master.

Other information (browser name/version, screenshots, etc.):
VE is an optional dependency to MF, and therefore the latter should work even if the former is not available. The code in question (introduced in r434730, 2023-06-09) is:

isVEVisualAvailable() {
	var config = mw.config.get( 'wgVisualEditorConfig' );
	var visualEditorNamespaces = config.namespaces || [];

	return this.isVEAvailable() &&
		visualEditorNamespaces.indexOf( mw.config.get( 'wgNamespaceNumber' ) ) !== -1;
}

This should be rearranged to return early if isVEAvailable is false.