[Bug] Docfx 2.78.x requires Nodejs even when not using PDF features

[glb-cblin]

Describe the bug
With 2.78.1, we have the following error

DocfxException: Node.js executable is not found. Try to install Node.js or set the `PLAYWRIGHT_NODEJS_PATH` environment variable.                    

The same error does not occur with 2.74.1

Reproduce the bug
To execute, we are doing this in our CI (which is using image: mcr.microsoft.com/dotnet/sdk:8.0 in gitlab)

        - dotnet tool install --global docfx  
        - export PATH="${PATH}:/root/.dotnet/tools" #see https://github.com/dotnet/docfx/issues/8542        
        - docfx docfx.json

Full relevant log

$ docfx docfx.json
[...]
Creating output...
Searching built-in plugins in directory /root/.dotnet/tools/.store/docfx/2.78.1/docfx/2.78.1/tools/net8.0/any/...
No files are found with glob pattern apidoc/**.md, excluding obj/**,_site/**, under directory "/builds/xxx"
7 plug-in(s) loaded.
Building 2 file(s) in TocDocumentProcessor(BuildTocDocument)...
Building 2 file(s) in ResourceDocumentProcessor(ValidateResourceMetadata)...
Building 3 file(s) in ConceptualDocumentProcessor(BuildConceptualDocument=>ValidateConceptualDocumentMetadata)...
Building 152 file(s) in ManagedReferenceDocumentProcessor(BuildManagedReferenceDocument=>SplitClassPageToMemberLevel=>ValidateManagedReferenceDocumentMetadata=>ApplyOverwriteDocumentForMref=>FillReferenceInformation)...
/builds/xxx/index.md(7,1): warning InvalidFileLink: Invalid file link:(~/api/index.html).
/builds/xxx/index.md(9,1): warning InvalidFileLink: Invalid file link:(~/../).
Applying templates to 159 model(s)...
XRef map exported.
TypeInitializationException: The type initializer for 'Docfx.Pdf.PdfBuilder' 
threw an exception.
     DocfxException: Node.js executable is not found. Try to install Node.js or 
     set the `PLAYWRIGHT_NODEJS_PATH` environment variable.                     
       at void EnsurePlaywrightNodeJsPath() in PlaywrightHelper.cs:25           
       at cctor() in PdfBuilder.cs:53                                           
  at Task CreatePdf(string outputFolder)                                        
  at void <Execute>b__0() in DefaultCommand.cs:53                               
  at int Run(LogOptions options, Action run) in CommandHelper.cs:48             
  at int Execute(CommandContext context, Options options) in DefaultCommand.cs: 
     31                                                                         
  at Task<int> Execute(CommandContext context, CommandSettings settings) in     
     CommandOfT.cs:40                                                           
  at async Task<int> Execute(CommandTree leaf, CommandTree tree, CommandContext 
     context, ITypeResolver resolver, IConfiguration configuration) in          
     CommandExecutor.cs:[166](https://gitlab.com/xxx/app-collab/apps/-/jobs/8470774002#L166)

The problem does not occur with 2.74.1

        - dotnet tool install --global docfx  --version 2.74.1
        - export PATH="${PATH}:/root/.dotnet/tools" #see https://github.com/dotnet/docfx/issues/8542        
        - docfx docfx.json

$ docfx docfx.json
Using .NET Core SDK 8.0.404
[...]
Creating output...
Searching custom plugins in directory /root/.dotnet/tools/.store/docfx/2.74.1/docfx/2.74.1/tools/net8.0/any/...
No files are found with glob pattern apidoc/**.md, excluding obj/**,_site/**, under directory "/builds/xxx"
7 plug-in(s) loaded.
Building 2 file(s) in ResourceDocumentProcessor(ValidateResourceMetadata)...
Building 152 file(s) in ManagedReferenceDocumentProcessor(BuildManagedReferenceDocument=>SplitClassPageToMemberLevel=>ValidateManagedReferenceDocumentMetadata=>ApplyOverwriteDocumentForMref=>FillReferenceInformation)...
Building 2 file(s) in TocDocumentProcessor(BuildTocDocument)...
Building 3 file(s) in ConceptualDocumentProcessor(BuildConceptualDocument=>ValidateConceptualDocumentMetadata)...
/builds/xxx/index.md(7,1): warning InvalidFileLink: Invalid file link:(~/api/index.html).
/builds/xxx/index.md(9,1): warning InvalidFileLink: Invalid file link:(~/../).
Applying templates to 159 model(s)...
XRef map exported.
Build succeeded with warning.
    2 warning(s)
    0 error(s)

[glb-cblin]

Same bug with 2.78.0

[glb-cblin]

It works with 2.77.0, so it's caused by something introduced in 2.78.0

[glb-cblin]

Problem seems to come from #10066 by @filzrev

We'd like to avoid installing nodejs if not strictly necessary (i.e we are not using PDF)

[filzrev]

Reported issue is fixed by #10406.
And expected to be fixed in the latest version (2.78.2).

[glb-cblin]

Tested in 2.78.2, it works, thank you

[mayankbhatt1004]

I am still having an issue for the pdf features on 2.78.2 (framework net9.0), worked fine with 2.77.x

[filzrev]

@mayankbhatt1004

This issue is expected to be fixed in v2.78.2.
If you don't need pdf file generation. Set pdf generate options to false

If PDF file generation feature is required.
It needs to separately install Node.js. Because Node.js runtime is not bundled docfx 2.78.0 or later version.