Crash on gitignore cration when project dir is not set

[lukaszsamson]

https://elixirforum.com/t/vscode-autocomplete-doesnt-work-for-mix-created-projects/32624/9

20:59:57.669 [error] GenServer ElixirLS.LanguageServer.Server terminating
** (FunctionClauseError) no function clause matching in IO.chardata_to_string/1
    (elixir 1.10.3) lib/io.ex:572: IO.chardata_to_string(nil)
    (elixir 1.10.3) lib/path.ex:520: Path.join/2
    (elixir 1.10.3) lib/path.ex:491: Path.join/1
    (language_server 0.4.0) lib/language_server/server.ex:804: ElixirLS.LanguageServer.Server.create_gitignore/1
    (language_server 0.4.0) lib/language_server/server.ex:735: ElixirLS.LanguageServer.Server.set_settings/2
    (language_server 0.4.0) lib/language_server/server.ex:134: ElixirLS.LanguageServer.Server.handle_cast/2
    (stdlib 3.13) gen_server.erl:680: :gen_server.try_dispatch/4
    (stdlib 3.13) gen_server.erl:756: :gen_server.handle_msg/6
Last message: {:"$gen_cast", {:receive_packet, %{"jsonrpc" => "2.0", "method" => "workspace/didChangeConfiguration", "params" => %{"settings" => %{"elixirLS" => %{"dialyzerEnabled" => true, "dialyzerFormat" => "dialyzer", "dialyzerWarnOpts" => [], "fetchDeps" => true, "mixEnv" => "test", "projectDir" => "dialyzer", "suggestSpecs" => true, "trace" => %{"server" => "off"}}}}}}}
State: %ElixirLS.LanguageServer.Server{analysis_ready?: false, awaiting_contracts: [], build_diagnostics: [], build_ref: nil, build_running?: false, client_capabilities: %{"textDocument" => %{"codeAction" => %{"codeActionLiteralSupport" => %{"codeActionKind" => %{"valueSet" => ["", "quickfix", "refactor", "refactor.extract", "refactor.inline", "refactor.rewrite", "source", "source.organizeImports"]}}, "dynamicRegistration" => true, "isPreferredSupport" => true}, "codeLens" => %{"dynamicRegistration" => true}, "colorProvider" => %{"dynamicRegistration" => true}, "completion" => %{"completionItem" => %{"commitCharactersSupport" => true, "deprecatedSupport" => true, "documentationFormat" => ["markdown", "plaintext"], "preselectSupport" => true, "snippetSupport" => true, "tagSupport" => %{"valueSet" => [1]}}, "completionItemKind" => %{"valueSet" => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25]}, "contextSupport" => true, "dynamicRegistration" => true}, "declaration" => %{"dynamicRegistration" => true, "linkSupport" => true}, "definition" => %{"dynamicRegistration" => true, "linkSupport" => true}, "documentHighlight" => %{"dynamicRegistration" => true}, "documentLink" => %{"dynamicRegistration" => true, "tooltipSupport" => true}, "documentSymbol" => %{"dynamicRegistration" => true, "hierarchicalDocumentSymbolSupport" => true, "symbolKind" => %{"valueSet" => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26]}}, "foldingRange" => %{"dynamicRegistration" => true, "lineFoldingOnly" => true, "rangeLimit" => 5000}, "formatting" => %{"dynamicRegistration" => true}, "hover" => %{"contentFormat" => ["markdown", "plaintext"], "dynamicRegistration" => true}, "implementation" => %{"dynamicRegistration" => true, "linkSupport" => true}, "onTypeFormatting" => %{"dynamicRegistration" => true}, "publishDiagnostics" => %{"relatedInformation" => true, "tagSupport" => %{"valueSet" => [1, 2]}, "versionSupport" => false}, "rangeFormatting" => %{"dynamicRegistration" => true}, "references" => %{"dynamicRegistration" => true}, "rename" => %{"dynamicRegistration" => true, "prepareSupport" => true}, "selectionRange" => %{"dynamicRegistration" => true}, "signatureHelp" => %{"contextSupport" => true, "dynamicRegistration" => true, "signatureInformation" => %{"documentationFormat" => ["markdown", "plaintext"], "parameterInformation" => %{"labelOffsetSupport" => true}}}, "synchronization" => %{"didSave" => true, "dynamicRegistration" => true, "willSave" => true, "willSaveWaitUntil" => true}, "typeDefinition" => %{"dynamicRegistration" => true, "linkSupport" => true}}, "window" => %{"workDoneProgress" => true}, "workspace" => %{"applyEdit" => true, "configuration" => true, "didChangeConfiguration" => %{"dynamicRegistration" => true}, "didChangeWatchedFiles" => %{"dynamicRegistration" => true}, "executeCommand" => %{"dynamicRegistration" => true}, "symbol" => %{"dynamicRegistration" => true, "symbolKind" => %{"valueSet" => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26]}}, "workspaceEdit" => %{"documentChanges" => true, "failureHandling" => "textOnlyTransactional", "resourceOperations" => ["create", "rename", "delete"]}, "workspaceFolders" => true}}, dialyzer_diagnostics: [], dialyzer_sup: nil, load_all_modules?: false, needs_build?: false, project_dir: nil, received_shutdown?: false, requests: %{}, root_uri: "file:///Users/satoru/projects/learn-elixir/trying", settings: nil, source_files: %{}}
[Info  - 8:59:58 PM] Connection to server got closed. Server will restart.
Started ElixirLS v0.4.0
Elixir version: "1.10.3 (compiled with Erlang/OTP 22)"
Erlang version: "23"