Fields added after a forward table assignment are not inferred #1272

Description

A table assigned after a forward local declaration does not gain fields assigned later. This produces undefined-field at the assignment and causes exported module fields to be considered nullable.

The equivalent code with declaration and table initialization in one statement works without diagnostics.

This affects LuaSnip: luasnip/config.lua forward-declares c, assigns its table later, and then aliases c.setup = c.set_config. As a result, normal user configuration gets function require('luasnip').setup may be nil [need-check-nil].

Minimal reproduction

.emmyrc.json:

{}

split/config.lua:

local config

config = {
  set_config = function(user_config)
    return user_config or {}
  end,
}

config.setup = config.set_config

return config

split/api.lua:

local API = {}

API.setup = require('split.config').setup

return API

client.lua:

require('split.api').setup {}

Run emmylua_check ..

Actual behavior

split/config.lua:9:8: Undefined field `setup`. [undefined-field]
split/api.lua:3:37: Undefined field `setup`. [undefined-field]
client.lua:1:1: function require('split.api').setup may be nil [need-check-nil]

Expected behavior

No diagnostics. config is definitely assigned the table before config.setup is added, and setup is definitely assigned before the module is returned.

Changing only the first two declarations to initialize the local directly makes the diagnostics disappear:

local config = {
  set_config = function(user_config)
    return user_config or {}
  end,
}

Environment

• emmylua_check 0.25.1
• emmylua_ls 0.25.1
• Linux x86_64
• Real-world occurrence: https://github.com/L3MON4D3/LuaSnip/blob/642b0c595e11608b4c18219e93b88d7637af27bc/lua/luasnip/config.lua#L34-L38 and https://github.com/L3MON4D3/LuaSnip/blob/642b0c595e11608b4c18219e93b88d7637af27bc/lua/luasnip/config.lua#L146-L147