[ts-next-plugin] clean up unused proxy (#78539)
Cleaned up a leftover unused proxy following up on
https://github.com/vercel/next.js/pull/78237.
Besides being unused, there was an issue reported from a large
repository. The repository was a monorepo, and the apps' modules were
shared with each other. The user received an error:
```
[trace] <semantic> Response received: definitionAndBoundSpan (951). Request took 0 ms. Success: false .
Message: Error processing request. Cannot read properties of undefined (reading 'updateFromProject')
TypeError: Cannot read properties of undefined (reading 'updateFromProject')
at synchronizeHostData (...)
at Object.getProgram (...)
at getSource (...)
at getEntryInfo (...)
at proxy.getDefinitionAndBoundSpan
```
The issue begins when `getDefinitionAndBoundSpan` is triggered—typically
via `Cmd + Click` or even hovering(!) to view definitions, imports, or
module references. In our case, since the repository contains multiple
apps, each enabling the plugin, navigating across apps using `Cmd +
Click` caused `getDefinitionAndBoundSpan` to fire across multiple plugin
instances.
The root cause is that when `getDefinitionAndBoundSpan` is triggered, it
calls `synchronizeHostData()` and checks whether it is to update the
project by checking the `host.updateFromProject` exists. However, the
Language Service Host is somehow `undefined` (assuming memory is
overloaded due to initiating multiple plugins), so we received the error
above.
x-ref:
https://github.com/microsoft/TypeScript/blob/11e79327598db412a161616849041487673fadab/src/services/services.ts#L1692-L1693
If we clean up this `getDefinitionAndBoundSpan` proxy, the error above
will be gone, but `synchronizeHostData` is called pretty much every time
on language service requests, including `getSemanticDiagnostics` we are
still proxying — a potential issue we can't control that could happen
for complicated repositories like the above.
x-ref: [slack
thread](https://vercel.slack.com/archives/C03S8ED1DKM/p1744231020199229)
