Installing required packages fails if the system library is not writable and the user has no library

Describe the bug
If a user without any user-level R library gets a prompt asking if they want to install languageserver and they click yes, the process exits without bubbling up as a popup.

To Reproduce
Steps to reproduce the behavior:

1. Launch folder in VScode containing R files on a system without languageserver/jsonlite installed, and no user library for the working user.
2. Receive prompt to install languageserver
3. Process exits because system library is not writable.

Can you fix this issue by yourself? (We appreciate the help)

No

Expected behavior
I would expect VScode to either prompt me to create a new user library, it to be automatically created, or at least a popup describing what's wrong.

Environment (please complete the following information):

• OS: Linux
• VSCode Version: [1.88.1]
• R Version: 4.3.3
• vscode-R version: [e.g. 1.2.2]

Additional context
Add any other context about the problem here.

No files, tests, or entry points are named. Start by reproducing the installation prompt on Linux with no user library and a non-writable system library, then trace the extension's package-install flow. Done means the failure is surfaced clearly and the expected user-library behavior is covered by a regression test.