refactor: initialize version manager before plugin registration

[nugged]

Summary

• Initialize the Copilot language server version manager before registering the LSP plugin.
• Keep the existing storage path and server version sources unchanged.

Rationale

CopilotPlugin.register() can make the plugin available for LSP session startup. on_pre_start_async() checks version_manager.is_installed, which depends on plugin_storage_dir and server_version already being initialized. Setting those fields before registration avoids an AttributeError if startup is triggered before the remaining plugin_loaded() setup has completed.

Validation

• Syntax-checked plugin/__init__.py with Python compile(...).

[jfcherng]

Makes sense to me. Wondering will this resolves any existing issue?

[nugged]

Couldn't find an existing issue, ... can't live without ST, and this started to annoy me without Copilot and blocked other LSP things to start. So Fixed for myself,
and then... straight to PR! :)

In my case, and I suspect this was triggered by Sublime Text updating to a newer Python runtime, LSP-copilot failed during startup with:

Console:

Unable to initialize language server for LSP-copilot
Traceback (most recent call last):
  File ".../Library/Application Support/Sublime Text/Installed Packages/LSP.sublime-package/plugin/core/windows.py", line 303, in start_async
    plugin_class.on_pre_start_async(context)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
  File ".../Library/Application Support/Sublime Text/Installed Packages/LSP-copilot.sublime-package/plugin/client.py", line 172, in on_pre_start_async
    if not version_manager.is_installed:
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../Library/Application Support/Sublime Text/Installed Packages/LSP-copilot.sublime-package/plugin/version_manager.py", line 64, in is_installed
    return self.server_path.is_file()
           ^^^^^^^^^^^^^^^^
  File ".../Library/Application Support/Sublime Text/Installed Packages/LSP-copilot.sublime-package/plugin/version_manager.py", line 59, in server_path
    return self.versioned_server_dir / self.THIS_TARBALL_BIN_PATH
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../Library/Application Support/Sublime Text/Installed Packages/LSP-copilot.sublime-package/plugin/version_manager.py", line 54, in versioned_server_dir
    return self.plugin_storage_dir / f"v{self.server_version}"
           ^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'VersionManager' object has no attribute 'plugin_storage_dir'

The failure happened before the server process was launched, while on_pre_start_async() was checking version_manager.is_installed.

[rchl]

I think this bug is a side effect of the bug that was just fixed (but not released as of now) - sublimelsp/LSP#2951

[rchl]

The fix in LSP was released so this shouldn't happen anymore.

Up to maintainers whether they want this change or not. I guess it makes sense nonetheless.

[jfcherng]

I am fine to merge this since it makes sense even if it fixes nothing.

Thanks you all.