`insert into table as alias` not work with dynamic inserts

Hello.

This is the reproduction code:

const postgres = require('postgres')
const sql = postgres()

main()

async function main() {
  await sql`CREATE TABLE IF NOT EXISTS my_users (id serial, name text)`

  await sql`INSERT INTO my_users AS u (name) VALUES('name')` // work, with alias

  await sql`INSERT INTO my_users ${sql({name: 'name'})}` // work, with dynamic inserts

  await sql`INSERT INTO my_users AS u ${sql({name: 'name'})}` // not work, with both alias and dynamic inserts
  // error: PostgresError: syntax error at or near "$1"
}

version information:

PostgreSQL: 15
postgres: 3.3.1

Start with the JavaScript reproduction using postgres 3.3.1 and PostgreSQL 15, comparing the working aliased insert and dynamic insert with the failing combination. Trace the dynamic insert handling and verify that an INSERT using both a table alias and dynamic values executes without the reported syntax error.