[BUG] ClientSidePage.InstantiateDefaultebparts() method throw exception while creating modernpage.

[Satyarthsr]

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• PnP Samples - https://github.com/pnp/PnP
  [x]- PnP Sites Core - https://github.com/pnp/PnP-Sites-Core
• PnPjs - https://github.com/pnp/pnpjs
• PnP PowerShell - https://github.com/pnp/PnP-PowerShell

Environment

[x ] Office 365 / SharePoint Online
[ ] SharePoint 2016
[ ] SharePoint 2013

If SharePoint on-premises, what's exact CU version:

Expected or Desired Behavior

After creating a clientsidepage I should be able to get Aviailable Webparts to page using ClientSidePage.AvailableClientSideComponents(DefaultClientSideWebparts.Webpartname)

Observed Behavior

The Above statement throws an exception as NullReferenceException: Object Reference not set to an instance of an object.
DETAILS OF Error:
System.AggregateException
HResult=0x80131500
Message=One or more errors occurred.
Source=mscorlib
StackTrace:
at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
at System.Threading.Tasks.Task1.GetResultCore(Boolean waitCompletionNotification) at System.Threading.Tasks.Task1.get_Result()
at OfficeDevPnP.Core.Pages.ClientSidePage.AvailableClientSideComponents(String name)
at OfficeDevPnP.Core.Pages.ClientSidePage.AvailableClientSideComponents(DefaultClientSideWebParts webPart)
at Provisioning.ModernPages.Program.Main(String[] args) .This exception was originally thrown at this call stack:
[External Code]
Inner Exception 1:
NullReferenceException: Object reference not set to an instance of an object.

Steps to Reproduce

If you are reporting a bug please describe the steps to reproduce the bug in sufficient detail to allow testing. Only way to fix things properly, is to have sufficient details to reproduce it. If you are making a suggestion, you can delete this section.

var page=clientcontext.web.AddClientSidePage(xyz.aspx,true);
var component=page.AvailableClientSideComponents(DefaultClientSideWebParts webPart).

[ghost]

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