VSCode extension can't find nuget packages
I restored a missing nuget package using msbuild and now I can use msbuild to compile my project without errors. However, the language server can't seem to find it so I get
The type or namespace name 'whatever' could not be found (are you missing a using directive or an assembly reference?) as a Problem everywhere any part of that package is used. How can I tell the language server where nuget put the dll? (and how can I find that, in the first place?)