Bug: no-fallthrough rule doesn't work well with labeled statements

[marvinhagemeister]

maybeFlag: if (isFlagProp(i)) {
  const type = getTypeId(ctx, offset);
  const flags = readValue(ctx, offset, AST_PROP_INTERNAL_FLAGS);

  switch (i) {
    case AST_PROP_OPERATOR:
      switch (type) {
        case AstType.AssignmentExpression:
          return getAssignOperator(flags);
        case AstType.BinaryExpression:
          return getBinaryOperator(flags);
        case AstType.UpdateExpression:
          return (flags & Flags.UpdatePlusPlus) !== 0 ? "++" : "--";
        default:
          break maybeFlag; // <-- Errors here
      }
    case AST_PROP_PREFIX:
      return (flags & Flags.UpdatePrefix) !== 0;
    case AST_PROP_OPTIONAL:
      return (flags & Flags.FnOptional) !== 0;
    case AST_PROP_ASYNC:
      return (flags & Flags.FnAsync) !== 0;
    case AST_PROP_GENERATOR:
      return (flags & Flags.FnGenerator) !== 0;
  }
}