def METHOD_NAME(storage, enspath, ens_config, caplog, monkeypatch):
    """Run migration but fail due to missing config data. Expected behaviour is
    for the error to be logged but no exception be propagated.
    """
    monkeypatch.setattr(ens_config, "parameter_configs", {})
    monkeypatch.setattr(ert.storage, "open_storage", lambda: storage)
    # Sanity check: no ensembles are created before migration
    assert list(storage.ensembles) == []
    with caplog.at_level(logging.WARNING, logger="ert.storage.migration.block_fs"):
        bf._migrate_case_ignoring_exceptions(storage, enspath / "default_0")
    # No ensembles were created due to failure
    assert list(storage.ensembles) == []
    # Warnings are in caplog
    assert len(caplog.records) == 1
    assert caplog.records[0].message == (
        "Exception occurred during migration of BlockFs case 'default_0': "
        "'The key:SNAKE_OIL_PARAM is not in the ensemble configuration'"
    )