Lambda variables in `map()` function cannot be used as arguments to nested function calls

Prerequisites

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Summary

I am experiencing a problem with using lambda variables from map() function as arguments to nested function calls in DSC expressions whilst working on #1230.

Steps to reproduce

1. Create a DSC configuration with a map() expression that uses a lambda variable
2. Pass the lambda variable as an argument to a function within the map body
3. Execute the configuration

Example config:

$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
parameters:
  baseNetwork:
    type: string
    defaultValue: 10.144.0.0/20
  newPrefix:
    type: int
    defaultValue: 24
  subnetCount:
    type: int
    defaultValue: 5
resources:
  - name: Generate subnets
    type: Microsoft.DSC.Debug/Echo
    properties:
      output: "[map(range(0, parameters('subnetCount')), 'i', cidrSubnet(parameters('baseNetwork'), parameters('newPrefix'), i))]"

Expected behavior

The `map()` function should iterate over the range [0, 1, 2, 3, 4], pass each value as the lambda variable i, and successfully call `cidrSubnet()` with that variable as the third argument. The output should be an array of 5 subnet CIDR strings.

Actual behavior

ERROR Parser: Found error node parsing function

Error details

Environment data

Name                           Value
----                           -----
PSVersion                      7.5.4
PSEdition                      Core
GitCommitId                    7.5.4
OS                             Microsoft Windows 10.0.26100
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Version

dsc 3.2.0-preview.7

Visuals

No response

Start by reproducing the DSC configuration using map(), range(), and cidrSubnet() from the issue, then trace the expression parser where the nested function call reports an error node. Check how the map lambda variable is passed into function arguments. Done means the configuration executes successfully and produces an array of five subnet CIDR strings.