Sqlite, databse is locked

[forrackun]

hello, i am having database is locked issue.
i can reproduce in below minimal example. as far as i know a constrain violation should not lock for subsequent operations
can you help me :) ?
thank you

// example.go

package main

import (
	"fmt"
	"log"
	"os"

	"github.com/upper/db/v4"
	"github.com/upper/db/v4/adapter/sqlite"
)

var settings = sqlite.ConnectionURL{
	Database: `example.db`,
}

func main() {
	defer os.Remove(`example.db`)

	sess, err := sqlite.Open(settings)
	if err != nil {
		log.Fatalf("db.Open(): %q\n", err)
	}

	_, err = sess.SQL().Exec(`DROP TABLE IF EXISTS "example1";

	create table example1(
		id INTEGER PRIMARY KEY AUTOINCREMENT,
		slug text not null,
		subtype text not null,
		description text not null,
		group_id text not null,
		unique( slug, group_id)
	);`)

	if err != nil {
		log.Fatal(err)
	}

	//sess.SetMaxOpenConns(1)

	defer sess.Close()

	for range []int{1, 2, 3} {
		Insert(sess)
	}
}

func Insert(sess db.Session) {
	tbl := sess.Collection("example1")

	_, err := tbl.Insert(db.Cond{
		"slug":        "aa",
		"group_id":    "g1",
		"description": "asas",
		"subtype":     "asa",
	})
	fmt.Println(err)
}

<nil>
2021/08/27 11:00:55 upper/db: log_level=WARNING file=/home/madman/go/pkg/mod/github.com/upper/db/v4@v4.2.1/internal/sqladapter/session.go:646
        Session ID:     00001
        Query:          INSERT INTO "example1" ("description", "group_id", "slug", "subtype") VALUES (?, ?, ?, ?)
        Arguments:      []interface {}{"asas", "g1", "aa", "asa"}
        Error:          UNIQUE constraint failed: example1.slug, example1.group_id
        Time taken:     0.00055s
        Context:        context.Background

UNIQUE constraint failed: example1.slug, example1.group_id
2021/08/27 11:01:05 upper/db: log_level=WARNING file=/home/madman/go/pkg/mod/github.com/upper/db/v4@v4.2.1/internal/sqladapter/session.go:646
        Session ID:     00001
        Query:          INSERT INTO "example1" ("description", "group_id", "slug", "subtype") VALUES (?, ?, ?, ?)
        Arguments:      []interface {}{"asas", "g1", "aa", "asa"}
        Error:          upper: slow query
        Time taken:     10.01480s
        Context:        context.Background

database is locked

[forrackun]

db/internal/testsuite/sql_suite.go

Line 147 in 9b9ecf1

s.T().Skip(`Skipped due to a "database is locked" problem with concurrent transactions. See https://github.com/mattn/go-sqlite3/issues/274`)