Gorm db.AutoMigrate failed on postgres after adding new field to struct

GORM Playground Link

https://github.com/go-gorm/playground/pull/515

Description

I am using AutoMigrate as a method of database updates. But when I added some fields to the model, this function reported an error

database: postgres:14.4 gorm version v1.23.8

struct GameUser was

type GameUser struct {
    gorm.Model
    XXX1 string `gorm:"uniqueIndex;size:255"`
    XXX2 string `gorm:"size:255"`

    StatAb UserStat `gorm:"embedded;embeddedPrefix:stat_ab_"`
    StatRb UserStat `gorm:"embedded;embeddedPrefix:stat_rb_"`
    StatSb UserStat `gorm:"embedded;embeddedPrefix:stat_sb_"`
}

type UserStat struct {
    TotalMission         int
    WinRate              float64
    GroundDestroyCount   int
    FleetDestroyCount    int
    GameTime             string
    AviationDestroyCount int
    WinCount             int
    SliverEagleEarned    int64
    DeadCount            int
}

And i did some modification to struct GameUser

type GameUser struct {
    gorm.Model
    XXX1 string `gorm:"uniqueIndex;size:255"`
    XXX2 string `gorm:"size:255"`

    StatAb UserStat `gorm:"embedded;embeddedPrefix:stat_ab_"`
    StatRb UserStat `gorm:"embedded;embeddedPrefix:stat_rb_"`
    StatSb UserStat `gorm:"embedded;embeddedPrefix:stat_sb_"`

        // new fields
        GroundRateAb GroundRate `gorm:"embedded;embeddedPrefix:rate_ground_ab_"`
    GroundRateRb GroundRate `gorm:"embedded;embeddedPrefix:rate_ground_rb_"`
    GroundRateSb GroundRate `gorm:"embedded;embeddedPrefix:rate_ground_sb_"`
}

type UserStat struct {
    TotalMission         int
    WinRate              float64
    GroundDestroyCount   int
    FleetDestroyCount    int
    GameTime             string
    AviationDestroyCount int
    WinCount             int
    SliverEagleEarned    int64
    DeadCount            int
}

type GroundRate struct {
    GameCount              int
    GroundVehicleGameCount int
    TDGameCount            int
    HTGameCount            int
    SPAAGameCount          int
    GameTime               string
    GroundVehicleGameTime  string
    TDGameTime             string
    HTGameTime             string
    SPAAGameTime           string
    TotalDestroyCount      int
    AviationDestroyCount   int
    GroundDestroyCount     int
    FleetDestroyCount      int
}

If game_user not in the database, it works well, new table game_user will be created. But when the table game_user which created by old struct exists, AutoMigrate error occurs. Error is

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x855f1b]

goroutine 1 [running]:
gorm.io/driver/postgres.Migrator.AlterColumn.func1(0xc0012a16c0)
        C:/Users/Administrator/go/pkg/mod/gorm.io/driver/postgres@v1.3.8/migrator.go:272 +0x23b
gorm.io/gorm/migrator.Migrator.RunWithValue({{0x60?, 0xc0012c4150?, {0x12a00e0?, 0xc00071ecc0?}}}, {0xf34580?, 0xc0000f4800}, 0xc000117618)        
        C:/Users/Administrator/go/pkg/mod/gorm.io/gorm@v1.23.8/migrator/migrator.go:52 +0x13c
gorm.io/driver/postgres.Migrator.AlterColumn({{{0x0?, 0xc0012c4150?, {0x12a00e0?, 0xc00071ecc0?}}}}, {0xf34580?, 0xc0000f4800?}, {0xe7d4dd?, 0x0?})
        C:/Users/Administrator/go/pkg/mod/gorm.io/driver/postgres@v1.3.8/migrator.go:259 +0xb1
gorm.io/gorm/migrator.Migrator.MigrateColumn({{0x4b?, 0xc001277f50?, {0x12a00e0?, 0xc00071ecc0?}}}, {0xf34580, 0xc0000f4800}, 0xc0002503c0, {0x12a2640, 0xc00036a340})
        C:/Users/Administrator/go/pkg/mod/gorm.io/gorm@v1.23.8/migrator/migrator.go:481 +0x625
gorm.io/driver/postgres.Migrator.MigrateColumn({{{0x1?, 0xc001277f50?, {0x12a00e0?, 0xc00071ecc0?}}}}, {0xf34580, 0xc0000f4800}, 0xc0002503c0, {0x12a2640?, 0xc00036a340?})
        C:/Users/Administrator/go/pkg/mod/gorm.io/driver/postgres@v1.3.8/migrator.go:227 +0x95
gorm.io/gorm/migrator.Migrator.AutoMigrate.func1(0xc00031b500)
        C:/Users/Administrator/go/pkg/mod/gorm.io/gorm@v1.23.8/migrator/migrator.go:123 +0x193
gorm.io/gorm/migrator.Migrator.RunWithValue({{0x70?, 0xc00077d770?, {0x12a00e0?, 0xc00071ecc0?}}}, {0xf34580?, 0xc0000f4800}, 0xc000117c60)
        C:/Users/Administrator/go/pkg/mod/gorm.io/gorm@v1.23.8/migrator/migrator.go:52 +0x13c
gorm.io/gorm/migrator.Migrator.AutoMigrate({{0x0?, 0xc00077d770?, {0x12a00e0?, 0xc00071ecc0?}}}, {0xc000524280?, 0x0?, 0x0?})
        C:/Users/Administrator/go/pkg/mod/gorm.io/gorm@v1.23.8/migrator/migrator.go:101 +0x1ce
gorm.io/gorm.(*DB).AutoMigrate(0xc0004fe750?, {0xc000524280, 0x2, 0x2})
        C:/Users/Administrator/go/pkg/mod/gorm.io/gorm@v1.23.8/migrator.go:28 +0x43
github.com/axiangcoding/ax-web/data.autoMigrate(0xc000117e20?)

it appears something wrong here. Anyone facing the same issue?

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