An error is raised when generating a png

[JBBianchi]

What happened:
Generating a png for a workflow seems to throw an error under certain conditions:

What you expected to happen:
The png to be generated.

How to reproduce it:

• Create a workflow.json file containing:

{
  "id": "helloworld",
  "version": "1.0.0",
  "specVersion": "0.8",
  "name": "Hello World Workflow",
  "description": "Inject Hello World",
  "start": "hello state",
  "states": [
     {
        "name": "hello state",
        "type": "inject",
        "data": {
           "result": "Hello World!"
        },
        "end": true
     }
  ]
}

• ctrl+shift+p > Export Diagram to PNG (or Generate Diagram, will also fail)

Anything else we need to know?:
From Saad Ansari on Slack

It seems to be related to a incorrect handling of paths and/or expected inputs of the command.

The extension also relies on external services to generate the files which is not necessary as VSCode already packs browser's capatiblities to render the diagram.

Finally, the code base is scattered and difficult to debug.

Environment:
Tested on Win11 x64. Reported from MacOS.