Add a check for the ImportExcel module, if the AsExcel is used

InvokePowerShellNotebook.ps1

@@ -17,11 +17,15 @@ function Invoke-PowerShellNotebook {
  Write-Progress -Activity "Executing PowerShell code block - [$(Get-Date)]" -Status (-join $targetCode) -PercentComplete (($idx + 1) / $codeBlockCount * 100)
 
  if ($AsExcel) {
+ if (!(Get-Module -ListAvailable ImportExcel -ErrorAction SilentlyContinue)) {
+ throw "This feature requires the ImportExcel PowerShell module. Use 'Install-Module -Name ImportExcel' to get it from the PS Gallery."
+ }
+
  if ($idx -eq 0) {
  $notebookFileName = Split-Path $NoteBookFullName -Leaf
  $xlFileName = $notebookFileName -replace ".ipynb", ".xlsx"
 
- $xlfile = "{0}\{1}" -f $pwd.Path, $xlFileName
+ $xlfile = " { 0 }\ { 1 }" -f $pwd.Path, $xlFileName
  Remove-Item $xlfile -ErrorAction SilentlyContinue
  }