Luanalysis doesn't seem to understand manual nil check

[yhslai]

Environment

Name	Version
IDEA version	2023.1.3
Luanalysis version	1.4.0
OS	Windows 10

Preferences

Lua

Name	Setting
Language level	Lua 5.4

Type Safety

Name	Setting
Strict nil checks	☑️
Unknown type (any) is indexable	☑️
Unknown type (any) is callabale	☑️

What are the steps to reproduce this issue?

---@type string[] | nil
local strs = {"abc"}

if strs ~= nil then
    print(strs[1])
end

What happens?

Error: No such indexer '[1] found on type 'nil'

What were you expecting to happen?

No error.

Any other comments?

I'm not sure if it's intentional or not, but I think it should report error in this case. For example, in C#, if we do manual null check first:

private string? _str = null;
...
if(_str != null)
{
   _str.ToUpper();
}

It'll compile without problem.

Furthermore, what's the alternative? Put --[[---@not nil]] everywhere?