Compiler panic when instantiating generic struct with interface/sumtype reference

[wenxuanjun]

Describe the bug

The compiler panic when instantiating a generic struct. The panic occurs under a specific combination of conditions:

1. A generic struct (struct Queue[T]) is defined after the function (some_func) that instantiates it
2. The struct contains a field that is a reference/pointer to an interface, a sumtype, or the generic type itself (e.g., &Speaker, &Event, or &T)

If I change the field type to a concrete struct reference (e.g., &Cat) or move the struct definition before the usage, the code compiles successfully.

Reproduction Steps

interface Speaker {
	speak()
}

struct Cat {}

fn (c &Cat) speak() {}

struct EventA {
	a u32
}

struct EventB {
	b u32
}

type Event = EventA | EventB

fn some_func() {
	queue := Queue.new[Speaker]()
}

struct Queue[T] {
mut:
	data &T = unsafe { nil }
}

fn Queue.new[T]() Queue[T] {
	return Queue[T]{}
}

fn main() {
    some_func()
}

Expected Behavior

The code should compile successfully regardless of the declaration order.

Current Behavior

The compiler crashes with the following panic:

V panic: table.sym: invalid type (typ=ast.Type(0x0 = 0) idx=0). Compiler bug. This should never happen. Please report the bug using `v bug file.v`.

 v hash: d9f1e33
    pid: 0xc2127
    tid: 0xc2132
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:19978: at builtin___v_panic: Backtrace
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:37647: by v__ast__default_table_panic_handler
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:37653: by v__ast__Table_panic
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:38355: by v__ast__Table_sym
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:33408: by v__gen__c__Gen_expr_with_cast
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:55586: by v__gen__c__Gen_zero_struct_field
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:55369: by v__gen__c__Gen_struct_init
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:34569: by v__gen__c__Gen_expr
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:34565: by v__gen__c__Gen_expr
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:33564: by v__gen__c__Gen_expr_with_cast
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:37413: by v__gen__c__Gen_return_stmt
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:33000: by v__gen__c__Gen_stmt
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:32664: by v__gen__c__Gen_stmts_with_tmp_var
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:32503: by v__gen__c__Gen_stmts
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:43235: by v__gen__c__Gen_gen_fn_decl
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:42877: by v__gen__c__Gen_gen_fn_decl
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:42786: by v__gen__c__Gen_fn_decl
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:32888: by v__gen__c__Gen_stmt
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:32664: by v__gen__c__Gen_stmts_with_tmp_var
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:32503: by v__gen__c__Gen_stmts
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:31309: by v__gen__c__Gen_gen_file
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:31248: by v__gen__c__cgen_process_one_file_cb
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:33656: by sync__pool__process_in_thread
/tmp/v_1000/v2.01KBHPZTRSRMD1X332H4ZCPK7B.tmp.c:16430: by sync__pool__process_in_thread_thread_wrapper
0x7f2945c9698b: by ???

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.12 d9f1e33

Environment details (OS name and version, etc.)

V 0.4.12 d9f1e33

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