Failed method request_julia_config(::LanguageServerInstance)

[davidanthoff]

From crash reporting.

Error message:

MethodError: no method matching length(::Nothing)
Closest candidates are:
  length(!Matched::Core.SimpleVector) at essentials.jl:597
  length(!Matched::Base.MethodList) at reflection.jl:819
  length(!Matched::Core.MethodTable) at reflection.jl:893
  ... 

Stack trace:

MethodError:
   at request_julia_config(::LanguageServerInstance) (./scripts/languageserver/packages/LanguageServer/src/requests/workspace.jl76)
   at process(::LanguageServer.JSONRPC.Request{Val{:initialized},Dict{String,Any}}, ::LanguageServerInstance) (./scripts/languageserver/packages/LanguageServer/src/requests/init.jl132)
   at run(::LanguageServerInstance) (./scripts/languageserver/packages/LanguageServer/src/languageserverinstance.jl217)
   at top-level scope (./scripts/languageserver/main.jl28)
   at include (boot.jl328)
   at include_relative(::Module, ::String) (loading.jl1094)
   at include(::Module, ::String) (Base.jl31)
   at exec_options(::Base.JLOptions) (client.jl295)
   at _start() (client.jl464)

This would be easy enough to fix, but I'm still a bit confused because my understanding of the spec is that it can send an empty array, but not null, right? Maybe we should debug this once to make sure we understand what is going on before we fix it?