Execution example::

  load --table MissingModeScalar
  [
  {"_key": "key", "missing_add":    "nonexistent1"}
  ]
  # [[0,1337566253.89858,0.000355720520019531],1]
  load --table MissingModeScalar
  [
  {"_key": "key", "missing_ignore": "nonexistent2"}
  ]
  # [
  #   [
  #     -22,
  #     1337566253.89858,
  #     0.000355720520019531,
  #     "<MissingModeScalar.missing_ignore>: failed to cast to <MissingModeScalarReferred>: <\"nonexistent2\">",
  #     [
  #       [
  #         "grn_ra_cast_value",
  #         "lib/store.c",
  #         522
  #       ]
  #     ]
  #   ],
  #   1
  # ]
  load --table MissingModeScalar
  [
  {"_key": "key", "missing_nil":    "nonexistent3"}
  ]
  # [
  #   [
  #     -22,
  #     1337566253.89858,
  #     0.000355720520019531,
  #     "<MissingModeScalar.missing_nil>: failed to cast to <MissingModeScalarReferred>: <\"nonexistent3\">",
  #     [
  #       [
  #         "grn_ra_cast_value",
  #         "lib/store.c",
  #         522
  #       ]
  #     ]
  #   ],
  #   1
  # ]
  select --table MissingModeScalar
  # [
  #   [
  #     0,
  #     1337566253.89858,
  #     0.000355720520019531
  #   ],
  #   [
  #     [
  #       [
  #         1
  #       ],
  #       [
  #         [
  #           "_id",
  #           "UInt32"
  #         ],
  #         [
  #           "_key",
  #           "ShortText"
  #         ],
  #         [
  #           "missing_add",
  #           "MissingModeScalarReferred"
  #         ],
  #         [
  #           "missing_ignore",
  #           "MissingModeScalarReferred"
  #         ],
  #         [
  #           "missing_nil",
  #           "MissingModeScalarReferred"
  #         ]
  #       ],
  #       [
  #         1,
  #         "key",
  #         "nonexistent1",
  #         "",
  #         ""
  #       ]
  #     ]
  #   ]
  # ]
  select --table MissingModeScalarReferred
  # [
  #   [
  #     0,
  #     1337566253.89858,
  #     0.000355720520019531
  #   ],
  #   [
  #     [
  #       [
  #         1
  #       ],
  #       [
  #         [
  #           "_id",
  #           "UInt32"
  #         ],
  #         [
  #           "_key",
  #           "ShortText"
  #         ]
  #       ],
  #       [
  #         1,
  #         "nonexistent1"
  #       ]
  #     ]
  #   ]
  # ]
