Fix deadlock while initializing JSON language server

As it turns out both parking-lot and std's `RwLock` disallows taking
multiple read locks on the same thread

Co-Authored-By: Max Brunsfeld <max@zed.dev>
757f05042dJulia committed on 3/16/2023, 9:32:51 PMparent1fbdea6
1 file changedLine totals unavailable