VBA Error 91 - Object or With block Variable not set - vba

Question

Kindly do not mark duplicate as I have properly checked for other related solutions specific to Error 91 but none of those seem to fetch me the solution for the problem I am facing .
Am trying to convert my coreldraw files nested in various folders (about 500 files ) using the following VBA code but its either crashing the application or showing the Error 91 'Object or With Block Variable not set'. The same code absolutely works fine when used with the other Demo Set of files which i created to test.
One case I could presume is the file showing some dialog when processing the script. If yes how should I prevent those dialog boxes. Application.DisplayAlerts = False not working in coreldraw.
But however that case is only an assumption. Can someone help me find the problem. Heres the code
Sub NewFolder()
Dim FileSystem As Object
Dim HostFolder As String
HostFolder = "My folder Path"
Set FileSystem = CreateObject("Scripting.FileSystemObject")
DoFolder FileSystem.GetFolder(HostFolder)
End Sub
Sub DoFolder(folder)
Dim SubFolder
For Each SubFolder In folder.SubFolders
DoFolder SubFolder
Next
Dim File
For Each File In folder.Files
If InStr(File.Name, ".cdr") Then
Application.OpenDocument (File)
End If
Dim filepath As String
filepath = ActiveDocument.FullFileName
Dim doc1 As Document
Dim SaveOptions As StructSaveAsOptions
Set SaveOptions = CreateStructSaveAsOptions
Set doc1 = ActiveDocument
With SaveOptions
.EmbedVBAProject = True
.Filter = cdrCDR
.IncludeCMXData = False
.Range = cdrAllPages
.EmbedICCProfile = True
.Version = cdrVersion17
End With
doc1.SaveAs filepath, SaveOptions
doc1.Close
' Operate on each file
Next
End Sub

Answer 1

I'd say you must check if a valid corel draw file has been found
I don't know CorelDraw VBA but I'd assume you could get the following code as a good start:
Sub DoFolder(folder)
Dim SubFolder
For Each SubFolder In folder.SubFolders
DoFolder SubFolder
Next
Dim file
Dim doc1 As Document
Dim filepath As String
Dim SaveOptions As StructSaveAsOptions
For Each file In folder.Files
If InStr(file.Name, ".cdr") Then
Set doc1 = GetDocument(file) '<--| try and get a valid CorelDraw document with the given file: see 'GetDocument()' function at the bottom
If Not doc1 Is Nothing Then '<--| if you succeed then go on with your code
filepath = ActiveDocument.FullFileName
Set SaveOptions = CreateStructSaveAsOptions
With SaveOptions
.EmbedVBAProject = True
.Filter = cdrCDR
.IncludeCMXData = False
.Range = cdrAllPages
.EmbedICCProfile = True
.Version = cdrVersion17
End With
doc1.SaveAs filepath, SaveOptions
doc1.Close
End If
End If
' Operate on each file
Next
End Sub
Function GetDocument(file As Variant) As Document
On Error Resume Next
Set GetDocument = OpenDocument(file)
End Function
as a side note I collected all Dim statements outside loops not to have them run multiple time uselessly