ORM : The required field database is null, v panic

[Avey777]

Describe the bug

The required field database is null, v panic

Reproduction Steps

module main

import db.mysql
import time
import orm

fn db_mysql() !mysql.DB {
	mut mysql_config := mysql.Config{
		host:     'mysql2.sqlpub.com'
		port:     3307
		username: 'vcore_test'
		password: 'wfo8wS7CylT0qIMg'
		dbname:   'vcore_test'
	}
	mut conn := mysql.connect(mysql_config) or { return err }
	return conn
}

@[table: 'sys_users']
struct User {
pub:
	id         string     @[immutable; primary; sql: 'id'; sql_type: 'VARCHAR(255)'; unique]
	name       string     @[immutable; sql: 'username'; sql_type: 'VARCHAR(255)'; unique]
	created_at ?time.Time @[omitempty; sql_type: 'TIMESTAMP']
	updated_at time.Time  @[default: '0001-01-01T00:00:00 +00:00'; omitempty; sql_type: 'TIMESTAMP']
}

fn main() {
	mut db := db_mysql() or { panic('failed to connect to database') }
	defer { db.close() }

	mut result := sql db {
		select from User
	} or { panic(err) }
	dump(result)

	mut qb := orm.new_query[User](db)
	result1 := qb.select('id', 'username')!.query()!
	dump(result1)
}

Expected Behavior

success

Current Behavior

V panic: as cast: cannot cast orm.Null to string
v hash: 3b4c016
/tmp/v_1000/orm.01JRVGQJH83TA5PGMBGH7MTE7A.tmp.c:6880: at _v_panic: Backtrace
/tmp/v_1000/orm.01JRVGQJH83TA5PGMBGH7MTE7A.tmp.c:7272: by __as_cast
/tmp/v_1000/orm.01JRVGQJH83TA5PGMBGH7MTE7A.tmp.c:11887: by orm__QueryBuilder_T_main__User_map_row_T_main__User
/tmp/v_1000/orm.01JRVGQJH83TA5PGMBGH7MTE7A.tmp.c:12161: by orm__QueryBuilder_T_main__User_query_T_main__User
/tmp/v_1000/orm.01JRVGQJH83TA5PGMBGH7MTE7A.tmp.c:14849: by main__main
/tmp/v_1000/orm.01JRVGQJH83TA5PGMBGH7MTE7A.tmp.c:14987: by main

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.10 3b4c016

Environment details (OS name and version, etc.)

V full version	V 0.4.10 86536e4.3b4c016
OS	linux, Deepin 23
Processor	6 cpus, 64bit, little endian, Intel(R) Core(TM) i5-8500B CPU @ 3.00GHz
Memory	0.26GB/7.61GB
V executable	/home/Jengro/.vmr/versions/v_versions/v_latest/v
V last modified time	2025-04-15 00:10:48
V home dir	OK, value: /home/Jengro/.vmr/versions/v_versions/v_latest
VMODULES	OK, value: /home/Jengro/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /home/Jengro/Documents/Dev/v-product/vprod-workspase/example
Git version	git version 2.45.2
V git status	weekly.2025.14-48-g3b4c0165
.git/config present	true
cc version	cc (Deepin 12.3.0-17deepin8) 12.3.0
gcc version	gcc (Deepin 12.3.0-17deepin8) 12.3.0
clang version	Deepin clang version 17.0.6 (5deepin5)
tcc version	tcc version 0.9.28rc 2025-02-13 HEAD@f8bd136d (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 696c1d84
emcc version	N/A
glibc version	ldd (Debian GLIBC 2.38-6deepin7) 2.38

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