Hover returns nothing for a field accessed through a union type (T?, T|nil, A|B) on main #1321

Repro

---@class P
---@field x boolean doc of P.x

---@class Q
---@field y boolean doc of Q.y

---@type P
local plain = {}
---@type P?
local opt = {}
---@type P|nil
local pnil = {}
---@type P|Q
local pq = {}
---@alias PQ P|Q
---@type PQ
local alias = {}
print(plain.x, opt.x, pnil.x, pq.x, pq.y, alias.x)

Hover each field access on the last line:

On main, the hover request returns an empty result for these accesses: no type line and no description.
The same union written through an ---@alias works.

Impact

Optional types are everywhere. The same happens with an optional parameter: inside
---@param opts? P / local function f(opts), hovering opts.x shows nothing on main, while 0.25.1
shows doc of P.x.

Written with help from Claude Code.