@Then("the traversal will raise an error")
    public void theTraversalWillRaiseAnError() {
        assertNotNull(error);

        // consume the error now that it has been asserted
        error = null;
    }
Some implementations of {@link VertexProperty} are not {@code Serializable} and may lead to test failures when passed as
parameters. One such instance is {@code HadoopVertexProperty}. This method detaches vertex properties as tests
should never require implementation-specific elements.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/features/StepDefinition.java