jsgen: using aliases in structures causes init errors

[gchumillas]

Describe the bug

Using aliases in structures causes init errors.

Reproduction Steps

Write a small app:

type String = string

struct Foo {
	// name string // OK!
	name String    // Not OK
}

fn main() {
	b := Foo{}

	// Cannot read properties of undefined (reading 'valueOf')
	assert b.name == ''
}

Compile to JavaScript and execute it:

v -b js main.v
node main.js

Output:

Cannot read properties of undefined (reading 'valueOf')

Expected Behavior

It should works fine.

Current Behavior

It throws an error.

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.10 0a37c22

Environment details (OS name and version, etc.)

V full version	V 0.4.10 dead5e6.0a37c22
OS	macos, macOS, 15.4.1, 24E263
Processor	8 cpus, 64bit, little endian, Apple M1 Pro
Memory	0.16GB/16GB
V executable	/Users/gonzalo/Projects/Personal/v/nv/v
V last modified time	2025-05-13 15:05:39
V home dir	OK, value: /Users/gonzalo/Projects/Personal/v/nv
VMODULES	OK, value: /Users/gonzalo/.vmodules
VTMP	OK, value: /tmp/v_501
Current working dir	OK, value: /Users/gonzalo/Projects/Personal/v/nv
Git version	git version 2.39.1
V git status	weekly.2025.19-25-g0a37c22e
.git/config present	true
cc version	Apple clang version 17.0.0 (clang-1700.0.13.3)
gcc version	Apple clang version 17.0.0 (clang-1700.0.13.3)
clang version	Apple clang version 17.0.0 (clang-1700.0.13.3)
tcc version	tcc version 0.9.28rc 2024-02-05 HEAD@105d70f7 (AArch64 Darwin)
tcc git status	thirdparty-macos-arm64 e447816c
emcc version	N/A
glibc version	N/A

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[huly-for-github]

Connected to Huly®: V_0.6-22844