Omnisharp failing to load solution file

[cdimitroulas]

Hi there,

This may be an upstream issue with the Omnisharp LSP itself but thought it would be worthwhile to start investigating on the nvim plugins side of things before looking into the LSP itself to see if there's an issue there.

Recently I started getting errors from the LSP saying that it was unable to load one of the projects in my solution. I can't figure out what is causing this error and this is making it very difficult to work on that particular project and even some other ones as all the diagnostics are completely wrong.

Here are the most relevant errors from the log file as far as I can tell:

[ERROR][2022-02-07 20:03:02] ...lsp/handlers.lua:404	'OmniSharp.MSBuild.ProjectLoader: The "ValidateExecutableReferences" task failed unexpectedly.\nSystem.NullReferenceException: Object reference not set to an instance of an object\n  at Microsoft.NET.Build.Tasks.ValidateExecutableReferences.ExecuteCore () [0x0006f] in <2484139272f6463f86e566118b7d8028>:0 \n  at Microsoft.NET.Build.Tasks.TaskBase.Execute () [0x0002e] in <2484139272f6463f86e566118b7d8028>:0 \n  at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute () [0x00029] in <9adaf83a4a1e41c79c53523270b5b9b8>:0 \n  at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask (Microsoft.Build.BackEnd.ITaskExecutionHost taskExecutionHost, Microsoft.Build.BackEnd.Logging.TaskLoggingContext taskLoggingContext, Microsoft.Build.BackEnd.TaskHost taskHost, Microsoft.Build.BackEnd.ItemBucket bucket, Microsoft.Build.BackEnd.TaskExecutionMode howToExecuteTask) [0x002fc] in <9adaf83a4a1e41c79c53523270b5b9b8>:0  | '
[ERROR][2022-02-07 20:03:02] ...lsp/handlers.lua:404	'OmniSharp.MSBuild.ProjectLoader: The "ValidateExecutableReferences" task failed unexpectedly.\nSystem.NullReferenceException: Object reference not set to an instance of an object\n  at Microsoft.NET.Build.Tasks.ValidateExecutableReferences.ExecuteCore () [0x0006f] in <2484139272f6463f86e566118b7d8028>:0 \n  at Microsoft.NET.Build.Tasks.TaskBase.Execute () [0x0002e] in <2484139272f6463f86e566118b7d8028>:0 \n  at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute () [0x00029] in <9adaf83a4a1e41c79c53523270b5b9b8>:0 \n  at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask (Microsoft.Build.BackEnd.ITaskExecutionHost taskExecutionHost, Microsoft.Build.BackEnd.Logging.TaskLoggingContext taskLoggingContext, Microsoft.Build.BackEnd.TaskHost taskHost, Microsoft.Build.BackEnd.ItemBucket bucket, Microsoft.Build.BackEnd.TaskExecutionMode howToExecuteTask) [0x002fc] in <9adaf83a4a1e41c79c53523270b5b9b8>:0  | '
[WARN][2022-02-07 20:03:02] ...lsp/handlers.lua:406	"OmniSharp.MSBuild.ProjectManager: Failed to load project file '/home/cdimitroulas/code/Theorem/BSI/accord/src/dotnet/ingestion/src/Accord.Standards.Api/Accord.Standards.Api.csproj'. | "
[WARN][2022-02-07 20:03:02] ...lsp/handlers.lua:406	"OmniSharp.MSBuild.ProjectManager: Failed to load project file '/home/cdimitroulas/code/Theorem/BSI/accord/src/dotnet/ingestion/src/Accord.Standards.Api/Accord.Standards.Api.csproj'. | "

And here is the relevant part from my lua config:

vim.lsp.set_log_level("warn")

-- keymaps
local on_attach = function(client, bufnr)
  local function buf_set_keymap(...) vim.api.nvim_buf_set_keymap(bufnr, ...) end
  local function buf_set_option(...) vim.api.nvim_buf_set_option(bufnr, ...) end

  buf_set_option('omnifunc', 'v:lua.vim.lsp.omnifunc')

  -- Mappings.
  local opts = { noremap=true, silent=true }
  buf_set_keymap('n', 'gd', '<Cmd>lua vim.lsp.buf.definition()<CR>', opts)
  buf_set_keymap('n', 'gD', '<Cmd>lua vim.lsp.buf.declaration()<CR>', opts)
  buf_set_keymap('n', 'gy', '<Cmd>lua vim.lsp.buf.type_definition()<CR>', opts)
  buf_set_keymap('n', 'gi', '<Cmd>lua vim.lsp.buf.implementation()<CR>', opts)
  buf_set_keymap('n', 'gr', '<Cmd>lua vim.lsp.buf.references()<CR>', opts)
  buf_set_keymap('n', 'K', '<Cmd>lua vim.lsp.buf.hover()<CR>', opts)
  buf_set_keymap('n', 'gH', '<Cmd>lua vim.lsp.buf.signature_help()<CR>', opts)
  buf_set_keymap('n', '[g', '<Cmd>lua vim.diagnostic.goto_prev()<CR>', opts)
  buf_set_keymap('n', ']g', '<Cmd>lua vim.diagnostic.goto_next()<CR>', opts)
  buf_set_keymap('n', '<leader>rn', '<cmd>lua vim.lsp.buf.rename()<CR>', opts)
  buf_set_keymap('n', '<space>e', '<cmd>lua vim.lsp.diagnostic.show_line_diagnostics()<CR>', opts)
  buf_set_keymap('n', 'ga', '<Cmd>lua vim.lsp.buf.code_action()<CR>', opts)

  -- Set some keybinds conditional on server capabilities
  if client.resolved_capabilities.document_formatting then
    buf_set_keymap("n", "<leader>f", "<cmd>lua vim.lsp.buf.formatting()<CR>", opts)
  elseif client.resolved_capabilities.document_range_formatting then
    buf_set_keymap("n", "<leader>f", "<cmd>lua vim.lsp.buf.range_formatting()<CR>", opts)
  end
end

local capabilities = require('cmp_nvim_lsp').update_capabilities(vim.lsp.protocol.make_client_capabilities())
-- enables snippet support
-- capabilities.textDocument.completion.completionItem.snippetSupport = true

local function make_config()
  return {
    capabilities = capabilities,
    -- map buffer local keybindings when the language server attaches
    on_attach = on_attach,
  }
end

local lsp_installer = require("nvim-lsp-installer")

-- Register a handler that will be called for all installed servers.
-- Alternatively, you may also register handlers on specific server instances instead (see example below).
lsp_installer.on_server_ready(function(server)
    local opts = make_config()

    -- (optional) Customize the options passed to the server
    -- if server.name == "tsserver" then
    --     opts.root_dir = function() ... end
    -- end

    if server.name == "sumneko_lua" then
      opts.settings = {
        Lua = {
          diagnostics = {
              globals = { 'vim' }
          }
        }
      }
    end

    -- Add typescript-tshm-plugin to tsserver for tshm
    -- type annotations on hover <3
    if server.name == "tsserver" then
      opts.init_options = {
        plugins = {
          {
            name = "typescript-tshm-plugin",
            location = "/home/cdimitroulas/.nvm/versions/node/v16.5.0/lib/node_modules/typescript-tshm-plugin/"
          }
        }
      }
    end

    -- This setup() function is exactly the same as lspconfig's setup function.
    -- Refer to https://github.com/neovim/nvim-lspconfig/blob/master/ADVANCED_README.md
    server:setup(opts)
end)

-- Manually setup F# LSP as it's not yet supported in nvim-lsp-installer
local fsharpConfig = {
  cmd = { 'dotnet', 'fsautocomplete', '--background-service-enabled' },
  root_dir = require'lspconfig/util'.root_pattern('*.sln', '*.fsproj', '.git'),
  filetypes = { 'fsharp' },
  init_options = {
    AutomaticWorkspaceInit = true,
  },
  capabilities = capabilities,
  on_attach = on_attach
  }

require'lspconfig'.fsautocomplete.setup(fsharpConfig)

Versions:

• neovim: 0.6.1
• nvim-lsp: latest version
• nvim-lsp-installer: latest version

(Literally just updated the package to see if that would solve anything, so they are the latest and greatest)