Provide better error message if Python 3.6 or older is used to start the language server

Describe the problem I am not able to get it to work at all.

To Reproduce

1. Connect vscode to a remote vscode.
2. Install plugin remote
3. config settings like bellow
4. open .robot file and the keywords are not recognized
5. Plugin Output log 3 files: https://gist.github.com/axi92/72b0b4d9df40da18c5012a9b75652447

Screenshots

Versions:

• OS: Local Ubuntu 20.04 Remote Ubuntu 18.04
• Robot Framework Version: 4.1.3
• Robot Framework Language Server Version: 0.40.1
• Client Version: VSCode 1.64.2

Logs

• 3 files https://gist.github.com/axi92/72b0b4d9df40da18c5012a9b75652447

settings.json

{
  "[robot]": {
    "editor.tabSize": 4,
    "editor.insertSpaces": true
  },
  "files.watcherExclude": {
    "**/.git/objects/**": true,
    "**/.git/subtree-cache/**": true,
    "**/node_modules/*/**": true,
    "**/libspecs/**": true,
    "**/Log/**": true
  },
  "terminal.integrated.fontFamily": "monospace",
  "robot.language-server.python": "/usr/bin/python3.8",
  "robot.python.executable": "/usr/bin/python2.7",
  "robot.language-server.args": ["-vv", "--log-file=/home/user/repo/system-life-cycle/looog/robotframework_ls.log"],
  "robot.completions.keywords.format": "Title Case",
  "robot.editor.4spacesTab": true,
  "robot.codeFormatter": "builtinTidy",
  "robot.libraries.libdoc.preGenerate": [
    "BuiltIn",
    "Collections",
    "DateTime",
    "Dialogs",
    "Easter",
    "OperatingSystem",
    "Process",
    "Reserved",
    "Screenshot",
    "String",
    "Telnet",
    "XML",
    "AppiumLibrary",
    "DatabaseLibrary",
    "Selenium2Library",
    "SSHLibrary",
    "JSONLibrary",
    "MQTTLibrary",
    "WebSocketClient"
  ]
}

[fabioz]

You can leave it open (as I repurposed it to provide a better error in this case in the future…).

[fabioz]

As a note, the docs aren’t entirely correct. You can use the following variables:

${workspace}, ${workspaceRoot}, ${workspaceFolder} and ${env.ENV_NAME_VARIABLE} or ${env:ENV_NAME_VARIABLE} for the value of robot variables (this was added but docs still don’t reflect that).

I’ll update the docs to address shortly…