fix: load env variable without value

lua/cmp-dotenv/load.lua

@@ -49,7 +49,8 @@ function M.load_data_from_text(content)
  local line = lines_arr[v]
  if not (line == nil or line == '') and string.sub(line, 1, 1) ~= '#' then
  local raw_values = split_str(line, '=')
- data_loaded[raw_values[1]] = { value = vim.trim(raw_values[2]), docs = docs and vim.trim(docs) or nil }
+ local value = raw_values[2] and vim.trim(raw_values[2]) or ''
+ data_loaded[raw_values[1]] = { value = value, docs = docs and vim.trim(docs) or nil }
  docs = nil
  else
  docs = (docs or '') .. vim.trim(string.sub(line, 2)) .. '\n'