Synopsis set to placeholder when description is missing

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest version
• Search the existing issues.

Steps to reproduce

Issue - synopsis without description:

function Synopsis {
<#
.SYNOPSIS
demo
#>
param()
}

(Get-help Synopsis).Synopsis
demo
(New-CommandHelp (Get-Command Synopsis)).Synopsis
{{ Fill in the Synopsis }}

With description:

function SynopsisAndDesc {
<#
.SYNOPSIS
demo
.DESCRIPTION
demo desc
#>
param()
}

(Get-help SynopsisAndDesc).Synopsis
demo
(New-CommandHelp (Get-Command SynopsisAndDesc)).Synopsis
demo

Expected behavior

(Get-help Synopsis).Synopsis
demo
(New-CommandHelp (Get-Command Synopsis)).Synopsis
demo

Actual behavior

(Get-help Synopsis).Synopsis
demo
(New-CommandHelp (Get-Command Synopsis)).Synopsis
{{ Fill in the Synopsis }}

Error details

Environment data

Name                           Value
----                           -----
PSVersion                      7.6.4
PSEdition                      Core
GitCommitId                    7.6.4
OS                             Microsoft Windows 10.0.26200
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.4
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Version

1.0.3

Visuals

No response

Start by reproducing the PowerShell examples with Get-help and New-CommandHelp, then trace the New-CommandHelp path that handles a missing .DESCRIPTION. Confirm the fix by ensuring the generated synopsis is "demo" rather than "{{ Fill in the Synopsis }}" for the Synopsis function, while the existing description case remains unchanged.