Exception in thread "main" java.sql.SQLException: After end of result set

Quando tento compilar aparece a seguinte erro de Exception: After end of result set. Alguém poderia me ajudar?

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class CategoriaDAO {

    private Connection connection;

    public CategoriaDAO(Connection connection) {
        this.connection = connection;

    }

    public List<Categoria> listar() throws SQLException {
        List<Categoria> categorias = new ArrayList<>();

        System.out.println("Executando a query de listar categoria");

        String sql = "SELECT ID, NOME FROM CATEGORIA";

        try (PreparedStatement pstm = connection.prepareStatement(sql)) {
            pstm.execute();

            try (ResultSet rst = pstm.getResultSet()) {
                while (rst.next()) {
                    Categoria categoria = new Categoria(rst.getInt(1), rst.getString(2));

                    categorias.add(categoria);
                }
            }
            return categorias;

        }
    }

    public List<Categoria> listarComProdutos() throws SQLException {
        Categoria ultima = null;
        List<Categoria> categorias = new ArrayList<>();

        System.out.println("Executando a query de listar categoria");

        String sql = "SELECT C.ID, C.NOME, P.ID, P.NOME, P.DESCRICACAO FROM CATEGORIA C INNER JOIN"
                + " PRODUTO P ON C.ID = P.CATEGORIA_ID"
                + " ORDER BY P.CATEGORIA_ID";

        try (PreparedStatement pstm = connection.prepareStatement(sql)) {
            pstm.execute();

            try (ResultSet rst = pstm.getResultSet()) {
                while (rst.next()) {
                    if (ultima == null || !ultima.getNome().equals(rst.getString(2))) {

                    }
                    Categoria categoria = new Categoria(rst.getInt(1), rst.getString(2));
                    ultima = categoria;
                    categorias.add(categoria);
                }
                Produto produto = new Produto(rst.getInt(3), rst.getString(4), rst.getString(5));
                ultima.adicionar(produto);
            }
        }
        return categorias;
    }
}

Stack Trace: 

jun. 14, 2021 10:22:32 PM com.mchange.v2.log.MLog 
INFO: MLog clients using java 1.4+ standard logging.
jun. 14, 2021 10:22:32 PM com.mchange.v2.c3p0.C3P0Registry 
INFO: Initializing c3p0-0.9.5.4 [built 23-March-2019 23:00:48 -0700; debug? true; trace: 10]
jun. 14, 2021 10:22:32 PM com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource 
INFO: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> 1br9pflai3oh99cjalmjb|16022d9d, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> null, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1br9pflai3oh99cjalmjb|16022d9d, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> jdbc:mysql://localhost/loja_virtual1?useTimezone=true&serverTimezone=UTC, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 15, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 3, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {password=******, user=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
Executando a query de listar categoria
Exception in thread "main" java.sql.SQLException: After end of result set
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63)
    at com.mysql.cj.jdbc.result.ResultSetImpl.checkRowPos(ResultSetImpl.java:484)
    at com.mysql.cj.jdbc.result.ResultSetImpl.getObject(ResultSetImpl.java:1283)
    at com.mysql.cj.jdbc.result.ResultSetImpl.getInt(ResultSetImpl.java:786)
    at com.mchange.v2.c3p0.impl.NewProxyResultSet.getInt(NewProxyResultSet.java:425)
    at CategoriaDAO.listarComProdutos(CategoriaDAO.java:60)
    at TestaListagemDeCategorias.main(TestaListagemDeCategorias.java:11)