lsp-unconfig-buffer is ran even when there is still one active client, therefore no code completions

Thank you for the bug report

[X] I am using the latest version of lsp-mode related packages.
[X] I checked FAQ and Troubleshooting sections
[X] You may also try reproduce the issue using clean environment using the following command: M-x lsp-start-plain

Bug description

lsp-unconfig-buffer is ran even when there is still one active client

it disables lsp-completion-mode.

Steps to reproduce

Install typescript-language-server but don't install angular server
Open an .ts file in an sample angular project (ng new --skip-install --defaults my-test-lsp)

Expected behavior

lsp-completion-mode and lsp-managed-mode are active in those buffers.

Observed: After step 2:

LSP :: angular-ls has exited (exited abnormally with code 1)
Server angular-ls:89021/starting exited with status exit(check corresponding stderr buffer for details). Do you want to restart it? (y or n) n

Then many features are disabled such as code completions, breadcrumb while ts-ls is perfectly capable of providing those functionalities.

Which Language Server did you use?

typescript-language-server angular-language-server (lsp-mode tried to connect but failed because it wasn't installed)

OS

Linux

Error callstack

No response

Anything else?