message: take .isDefined into account in CifField.ofColumn
diff: @@ -222,7 +222,7 @@ export namespace CifField {
  }
  export function ofColumn(column: Column<any>): CifField {
  - const { rowCount, valueKind, areValuesEqual } = column;
  + const { rowCount, valueKind, areValuesEqual, isDefined } = column;
  let str: CifField['str']
  let int: CifField['int']
  @@ -253,7 +253,7 @@ export namespace CifField {
  return {
  __array: void 0,
  binaryEncoding: void 0,
  - isDefined: true,
  + isDefined,
  rowCount,
  str,
  int,
  