Error occurs if `analysis_unit_dirs` is not set

[sinsoku]

The file generated by typeprof --init are as follows.

{
  "typeprof_version": "experimental",
  "rbs_dir": "sig/"
  // "analysis_unit_dirs": [],
  // "diagnostic_severity": "warning"
}

However, when I start TypeProf with this file, an error occurs.

/Users/sinsoku/ghq/github.com/ruby/typeprof/lib/typeprof/lsp/server.rb:107:in 'block in TypeProf::LSP::Server#add_workspaces': undefined method 'each' for nil (NoMethodError)

            conf[:analysis_unit_dirs].each do |dir|
                                     ^^^^^
	from /Users/sinsoku/ghq/github.com/ruby/typeprof/lib/typeprof/lsp/server.rb:79:in 'Array#each'
	from /Users/sinsoku/ghq/github.com/ruby/typeprof/lib/typeprof/lsp/server.rb:79:in 'TypeProf::LSP::Server#add_workspaces'
	from /Users/sinsoku/ghq/github.com/ruby/typeprof/lib/typeprof/lsp/messages.rb:64:in 'TypeProf::LSP::Message::Initialize#run'