System.NotImplementedException when using for loop and spread operator in the same resource definition

[BalassaMarton]

Bicep version

> bicep version
Bicep CLI version 0.30.23 (ec3612efc7)

Describe the bug
When I try to use a for loop and the spread operator inside the same resource definition, I get this error: System.NotImplementedException: Cannot emit unexpected expression of type ForLoopExpression

To Reproduce

// Bicep-spread-test.bicep
param databaseName string
param locations string[]
param setIpRules bool = false
param ipAddresses string[]?
param addAzurePortalIPAddresses bool = false

var azurePortalIPAddresses = [
  '13.88.56.148'
  '40.91.218.243'
  '13.91.105.215'
  '4.210.172.107'
]

var allIpAddresses = union((ipAddresses ?? []), addAzurePortalIPAddresses ? azurePortalIPAddresses : [])

var ipRules = setIpRules ? { ipRules: map(allIpAddresses, ip => { ipAddressOrRange: ip }) } : {}

resource database 'Microsoft.DocumentDB/databaseAccounts@2024-05-15' = {
  name: databaseName
  location: 'westus'
  kind: 'GlobalDocumentDB'
  properties: {
    databaseAccountOfferType: 'Standard'
    locations: [ for (location, idx) in locations: { locationName: location, failoverPriority: idx } ]
    ...ipRules
  }
}

az bicep build --stdout --file ./Bicep-spread-test.bicep

The error goes away if I extract the for loop in a variable, or remove usages of the spread operator.

[jeskew]

This may require #14106 to fully address. ARM copy properties (what for loops compile to) can't be used inside of a shallowMerge function (what spread operations compile to), so the loop would need to be translated to a map function expression for this work