cgen error: assign the spawn or go expr to the []thread

[shove70]

Describe the bug

v run a.v
==================
/tmp/v_501/a.12000158363956472078.tmp.c:2138:8: error: expected ';' at end of declaration
        int a1 });
              ^
              ;
/tmp/v_501/a.12000158363956472078.tmp.c:2138:10: error: expected identifier or '('
        int a1 });
                ^
/tmp/v_501/a.12000158363956472078.tmp.c:2139:20: error: expected ')'
         _v_dump_expr_int(_SLIT("a.v"), 6, _SLIT("a"), a);
                          ^
/tmp/v_501/a.12000158363956472078.tmp.c:183:27: note: expanded from macro '_SLIT'
#define _SLIT(s) ((string){.str=(byteptr)("" s), .len=(sizeof(s)-1), .is_lit=1})
...
==================
(Use `v -cg` to print the entire error message)

builder error: 
==================
C error. This should never happen.

This is a compiler bug, please report it using `v bug file.v`.

https://github.com/vlang/v/issues/new/choose

You can also use #help on Discord: https://discord.gg/vlang

Reproduction Steps

fn main() {
	mut threads := []thread{len: 1}

	threads[0] = spawn fn () {
		a := 1
		dump(a)
		assert true
	}()

	threads.wait()
}

Expected Behavior

no error.

Current Behavior

cgen error.

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.1 09006fa

Environment details (OS name and version, etc.)

V full version: V 0.4.1 09006fa
OS: macos, macOS, 13.5.2, 22G91
Processor: 8 cpus, 64bit, little endian, Intel(R) Core(TM) i7-8569U CPU @ 2.80GHz

getwd: /usr/local/v
vexe: /usr/local/v/v
vexe mtime: 2023-09-16 08:46:34

vroot: OK, value: /usr/local/v
VMODULES: OK, value: /Users/shove/.vmodules
VTMP: OK, value: /tmp/v_501

Git version: git version 2.39.2 (Apple Git-143)
Git vroot status: weekly.2023.30-315-g09006fa5
.git/config present: true

CC version: Apple clang version 14.0.3 (clang-1403.0.22.14.1)
thirdparty/tcc status: thirdparty-macos-amd64 46662e2

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