Error with symbol containing newlines

[ten3roberts]

Describe the bug
API error for nvim_buf_set_lines when a symbol/line contains newlines.

This happens for some language servers which return multiline symbols or empty symbols.

System information

• OS: linux
• Neovim version:NVIM v0.7.0-dev+1356-g75ff156d9 (issue has persisted in earlier versions)
• AerialInfo:

Aerial Info
-----------
Filetype: svelte
Configured backends:
  lsp (supported) (attached)
  treesitter (not supported) [No query file for 'svelte']
  markdown (not supported) [Filetype is not markdown]
Show symbols: Class, Constructor, Enum, Function, Interface, Module, Method, Struct

• Aerial config:

-- Call the setup function to change the default behavior
require("aerial").setup({
  backends = { "lsp", "treesitter", "markdown" },

  close_behavior = "global",

  default_bindings = true,
  default_direction = "prefer_left",

  disable_max_lines = 10000,

  highlight_mode = "split_width",

  -- When jumping to a symbol, highlight the line for this many ms.
  -- Set to false to disable
  highlight_on_jump = 300,

  icons = {
    Function = "ﬦ"
  },

  -- When you fold code with za, zo, or zc, update the aerial tree as well.
  -- Only works when manage_folds = true
  link_folds_to_tree = false,

  -- Fold code when you open/collapse symbols in the tree.
  -- Only works when manage_folds = true
  link_tree_to_folds = true,

  -- Use symbol tree for folding. Set to true or false to enable/disable
  -- 'auto' will manage folds if your previous foldmethod was 'manual'
  manage_folds = false,

  -- The maximum width of the aerial window
  max_width = 40,

  -- The minimum width of the aerial window.
  -- To disable dynamic resizing, set this to be equal to max_width
  min_width = 10,

  -- Set default symbol icons to use patched font icons (see https://www.nerdfonts.com/)
  -- "auto" will set it to true if nvim-web-devicons or lspkind-nvim is installed.
  nerd_font = "auto",

  -- Call this function when aerial attaches to a buffer.
  -- Useful for setting keymaps. Takes a single `bufnr` argument.
  on_attach = nil,

  -- Automatically open aerial when entering supported buffers.
  -- This can be a function (see :help aerial-open-automatic)
  open_automatic = true,

  -- Set to true to only open aerial at the far right/left of the editor
  -- Default behavior opens aerial relative to current window
  placement_editor_edge = true,

  -- Run this command after jumping to a symbol (false will disable)
  post_jump_cmd = "normal! zz",

  -- When true, aerial will automatically close after jumping to a symbol
  close_on_select = false,

  -- Show box drawing characters for the tree hierarchy
  -- show_guides = false,

  lsp = {
    -- Fetch document symbols when LSP diagnostics change.
    -- If you set this to false, you will need to manually fetch symbols
    diagnostics_trigger_update = true,

    -- Set to false to not update the symbols when there are LSP errors
    update_when_errors = true,
  },

  treesitter = {
    -- How long to wait (in ms) after a buffer change before updating
    update_delay = 300,
  },

  markdown = {
    -- How long to wait (in ms) after a buffer change before updating
    update_delay = 300,
  },

})

To Reproduce
Steps to reproduce the behavior:

1. Open aerial
2. Edit a svelte file with the svelte language server
3. Use an await block
   The issue also occurs in lua files when creating a new function and the symbol is empty, though it is not reliably reproduced. The underlying issue is symbol sanitation

{#await { foo }}
  <h1>Loading</h1>
{/await}

Screenshots

The following is the value which is supplied to nvim_buf_set_lines in render.lua:155 (using vim.inspect)

[stevearc]

Should be fixed. Thanks for the report!