generics, cgen: invalid cgen when mixing type aliases

[Le0Developer]

V doctor:

|V full version      |V 0.4.9 5b44b67.af1ef92
|:-------------------|:-------------------
|OS                  |macos, macOS, 15.2, 24C101
|Processor           |10 cpus, 64bit, little endian, Apple M4
|Memory              |0.4GB/16GB
|                    |
|V executable        |/Users/leodev/p/v/v/v
|V last modified time|2025-01-05 15:18:43
|                    |
|V home dir          |OK, value: /Users/leodev/p/v/v
|VMODULES            |OK, value: /Users/leodev/.vmodules
|VTMP                |OK, value: /tmp/v_501
|Current working dir |OK, value: /Users/leodev/p/v/fast2
|                    |
|Git version         |git version 2.47.0
|V git status        |weekly.2024.53-31-gaf1ef929 (1 commit(s) behind V master)
|.git/config present |true
|                    |
|cc version          |Apple clang version 16.0.0 (clang-1600.0.26.6)
|gcc version         |Apple clang version 16.0.0 (clang-1600.0.26.6)
|clang version       |Apple clang version 16.0.0 (clang-1600.0.26.6)
|tcc version         |tcc version 0.9.28rc 2024-02-05 HEAD@105d70f7 (AArch64 Darwin)
|tcc git status      |thirdparty-macos-arm64 713692d4
|emcc version        |N/A
|glibc version       |N/A

What did you do?
./v -g -o vdbg cmd/v && ./vdbg repro.v && repro

type I64 = i64

fn test[T](a ?T) ? {
	return none
}

fn main() {
	a := ?i64(123)
	b := test[I64](a)
	println(b)
}

What did you see?

================== C compilation error (from cc): ==============
cc: /tmp/v_501/repro.01JGVHF8TVE1GJF24R0361RXXP.tmp.c:5871:29: error: initializing 'main__I64' (aka 'long long') with an expression of incompatible type '_option_i64' (aka 'struct _option_i64')
cc:  5871 |         _option_ok(&(main__I64[]) {a }, (_option*)(&_t2), sizeof(main__I64));
cc:       |                                    ^
cc: 1 error generated.
================================================================
(You can pass `-cg`, or `-show-c-output` as well, to print all the C error messages).
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .

What did you expect to see?

Successful compilaton

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_{Huly®: V_0.6-21813}