Incorrect constraint name in duplicate key error — violates UNIQUE(email) but reports "user_pkey"

[AndrewSmithDev]

Describe the bug

When violating a UNIQUE constraint (e.g., on the email column), pg-mem throws an error referencing the primary key constraint (user_pkey) instead of the actual violated constraint (user_email_key).

This leads to misleading error messages and breaks error handling logic that inspects constraint names.

ERROR: insert into "user" (email, password, id) values ($1, $2, $3) returning "email" - duplicate key value violates unique constraint "user_pkey"
DETAIL: Key (email)=(user@example.com) already exists.

🐜 This seems to be an execution error, which means that your request syntax seems okay,
    but the resulting statement cannot be executed → Probably not a pg-mem error.

*⃣ Failed SQL statement:
      INSERT INTO "user" (email, password) VALUES ('user@example.com', 'anotherpass');
    ;

👉 You can file an issue at https://github.com/oguimbal/pg-mem along with a way to reproduce this error (if you can), and  the stacktrace:

To Reproduce

-- Schema
CREATE TABLE "user" (
  id SERIAL PRIMARY KEY,
  email TEXT NOT NULL,
  password TEXT NOT NULL,
  CONSTRAINT user_email_key UNIQUE (email)
);

-- Data
INSERT INTO "user" (email, password) VALUES ('user@example.com', 'password123');
-- This should fail due to UNIQUE(email), but error message incorrectly says "user_pkey"
INSERT INTO "user" (email, password) VALUES ('user@example.com', 'anotherpass');

Node alternative

const { newDb } = require("pg-mem");

(async () => {
  const db = newDb();

  // Create schema with primary key and named UNIQUE constraint
  await db.public.none(`
    CREATE TABLE "user" (
      id SERIAL PRIMARY KEY,
      email TEXT NOT NULL,
      password TEXT NOT NULL,
      CONSTRAINT user_email_key UNIQUE (email)
    );
  `);

  // Insert a user (valid)
  await db.public.none(`
    INSERT INTO "user" (email, password) VALUES ('user@example.com', 'password123');
  `);

  // Insert duplicate (violates email constraint, but error says user_pkey)
  try {
    await db.public.none(`
      INSERT INTO "user" (email, password) VALUES ('user@example.com', 'anotherpass');
    `);
  } catch (err) {
    console.error(err.message);
  }
})();

pg-mem version

3.0.5