fix(lsp): util.lua attempt to concatenate userdata #39225

Problem:
Error when querying document symbols using python-lsp-server:

    lsp/util.lua:1955: attempt to concatenate field 'containerName' (a userdata value)

Solution:
Check for `vim.NIL`.

runtime/lua/vim/_core/util.lua

@@ -166,4 +166,11 @@ function M.get_forge_url(repo, target, target_type)
   return ('%s/%s/%s'):format(repo, middle, target)
 end
 
+--- Check if value is `nil` or `vim.NIL`
+---
+--- @return boolean
+function M.isnil(value)
+  return value == nil or value == vim.NIL
+end
+
 return M

runtime/lua/vim/lsp/completion.lua

@@ -36,6 +36,7 @@ local M = {}
 local api = vim.api
 local lsp = vim.lsp
 local protocol = lsp.protocol
+local isnil = require('vim._core.util').isnil
 
 local rtt_ms = 50.0
 local ns_to_ms = 0.000001
@@ -1010,7 +1011,7 @@ local function trigger(bufnr, clients, ctx)
             client and client.name or 'UNKNOWN'
           )
         )
-      elseif result and result ~= vim.NIL and #(result.items or result) > 0 then
+      elseif not isnil(result) and #(result.items or result) > 0 then
         Context.isIncomplete = Context.isIncomplete or result.isIncomplete
         local encoding = client and client.offset_encoding or 'utf-16'
         local client_matches, tmp_server_start_boundary

runtime/lua/vim/lsp/util.lua

@@ -3,6 +3,7 @@ local validate = vim.validate
 local api = vim.api
 local list_extend = vim.list_extend
 local uv = vim.uv
+local isnil = require('vim._core.util').isnil
 
 local M = {}
 
@@ -1986,13 +1987,13 @@ function M.symbols_to_items(symbols, bufnr, position_encoding)
       local end_lnum = range['end'].line + 1
       local end_col = get_line_byte_from_position(bufnr, range['end'], position_encoding) + 1
 
-      local is_deprecated = symbol.deprecated
-        or (symbol.tags and vim.tbl_contains(symbol.tags, protocol.SymbolTag.Deprecated))
+      local is_deprecated = not isnil(symbol.deprecated or nil)
+        or (not isnil(symbol.tags) and vim.tbl_contains(symbol.tags, protocol.SymbolTag.Deprecated))
       local text = string.format(
         '[%s] %s%s%s',
         kind,
         symbol.name,
-        symbol.containerName and ' in ' .. symbol.containerName or '',
+        not isnil(symbol.containerName) and ' in ' .. symbol.containerName or '',
         is_deprecated and ' (deprecated)' or ''
       )
 

test/functional/plugin/lsp/util_spec.lua

@@ -629,7 +629,7 @@ describe('vim.lsp.util', function()
           filename = '/test_b',
           kind = 'Module',
           lnum = 4,
-          text = '[Module] TestB in TestBContainer (deprecated)',
+          text = '[Module] TestB (deprecated)',
         },
       }
       eq(
@@ -672,7 +672,7 @@ describe('vim.lsp.util', function()
                 },
                 uri = 'file:///test_b',
               },
-              containerName = 'TestBContainer',
+              containerName = vim.NIL,
             },
           }
           return vim.lsp.util.symbols_to_items(sym_info, nil, 'utf-16')