Error starting PowerShell 7.4.0+

Prerequisites

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• Make sure you are able to repro it on the latest released version
• Search the existing issues.
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• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

1. Install PowerShell 7.4.0
2. Start it
3. Create a powershell.config.json and set PSModulePath to multiple paths, separated by ; (path separator char) (see reference).
4. See it fail

Expected behavior

It starts, like 7.3 did.

Actual behavior

It fails with:

PowerShell 7.4.0
The shell cannot be started. A failure occurred during initialization:
Index was out of range. Must be non-negative and less than or equal to the size of the collection. (Parameter 'startIndex')

Error details

Not possible.

Environment data

Not possible, but it is version 7.4.0.

Visuals

This is starting from Nushell:

This is starting it from Windows Terminal:

Additional context

Downloaded and installed this file: https://github.com/PowerShell/PowerShell/releases/download/v7.4.0/PowerShell-7.4.0-win-x64.msi

I debugged and found out that the exception is ocurring at this location (ModuleIntrinsics.UpdatePath):
https://github.com/PowerShell/PowerShell/blob/ad2bf787e4e7dfde9123a67349cf1ae6ccdfc984/src/System.Management.Automation/engine/Modules/ModuleIntrinsics.cs#L1278

The arguments for UpdatePath are:
path: a string with a ; separated list of paths
pathToAdd: another string with a ; separated list of paths
insertIndex: 0

The call that is failing is the one to path.IndexOf, which is passed ; and -1 (which is the result from the call to PathContainsSubstring).

The problem only happens because pathToAdd has several paths with the ; separator. If it was a single path without ; it would work.

The issue seems to have been introduced in commit 3710671c16de9bcbd945389a22a88b994cd02bcd.

Start in src/System.Management.Automation/engine/Modules/ModuleIntrinsics.cs at ModuleIntrinsics.UpdatePath, focusing on the path.IndexOf call described in the issue. Reproduce the failure with a powershell.config.json whose PSModulePath contains multiple semicolon-separated paths, then verify that PowerShell 7.4 starts successfully with that configuration.