Followup improvements to LSP (#11430)

Addressing things brought up in https://github.com/neovim/neovim/issues/11389 and beyond.

- Bugfix for empty dictionary serialization.
- Reduce markdown previews of code.
- Refactor method triggers to `lsp.buf.*` methods
- Switch to v:lua and get rid of vim interface.
- Get rid of filetype config in favor of something from https://github.com/neovim/nvim-lsp
- Switch error messages to something which doesn't require `ENTER` because if an LSP goes crazy, it'll block neovim.
- Rename `builtin_callbacks` to `default_callbacks`
- Resolve callback at time of calling using default_callbacks instead of at client creation
- Make hover/signatureHelp preview focusable so you can mess with it.
- Add vim.lsp.util.set_qflist and vim.lsp.util.set_loclist and vim.lsp.util.locations_to_items().
- Add apply_textedit and tests which enables a new class of features.
- Fix column offsets in character and bytes in vim.lsp.buf to be correct.

New methods:
- Add textDocument/references under vim.lsp.buf.references()
- Finish textDocument/rename
- Finish textDocument/rangeFormatting and textDocument/format

1 files changed, 1 insertions, 0 deletions

diff --git a/runtime/lua/vim/lsp/rpc.lua b/runtime/lua/vim/lsp/rpc.lua
index e0ec8863d6..a558f66a42 100644
--- a/runtime/lua/vim/lsp/rpc.lua
+++ b/runtime/lua/vim/lsp/rpc.lua
@@ -340,6 +340,7 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
     local decoded, err = json_decode(body)
     if not decoded then
       on_error(client_errors.INVALID_SERVER_JSON, err)
+      return
     end
     local _ = log.debug() and log.debug("decoded", decoded)