Syntax error at or near $1

[chlin501]

I can successfully create code that reads data from Postgres database by following the explanation like [1]. The code looks like this

// through psql
// CREATE TABLE Person(id TEXT, name TEXT, age INT); 
// INSERT INTO Person VALUES ('1', 'John', 33);
// INSERT INTO Person VALUES ('2', 'Smith', 24);
const sql = postgres(`postgres://myusername:mypassword@localhost:5432/mydatabase`);
const result = await sql`SELECT (id, name, age) FROM PERSON;`; 
console.log(result[0]['row']);

But I have a problem when attempting to wrap the code into a class. For instance,

// typescript
class MyWrapper {
    sql: Sql;
    constructor(host: string, port: number, db: string, user: string, pass: string) {
        this.sql = postgres(`postgre://${user}:${pass}@${host}/${db}`)
    }
    async run(sqlstr: string) {
        await this.sql`${sqlstr}`; // this will cause syntax error at or near $1
        // await this.sql`${this.sql(sqlstr)}`; // this will cause syntax error at or near ""SELECT id, name, age FROM Person""
    }
}

// the code that calls the wrapper is as below
const postgresql = MyWrapper(...);
postgresql.run(`SELECT id, name, age FROM Person;`)  // this cause the syntax error at or near error.

This seems that it's related to [2], but I do not know to fix it. Any advice? Many thanks.

[1]. https://github.com/porsager/postgres?tab=readme-ov-file#usage
[2]. https://github.com/porsager/postgres?tab=readme-ov-file#quick-primer-on-interpolation