message: [hotfix] handle missing or empty column type
diff: @@ -117,15 +117,24 @@ class BaseColumn(AuditMixinNullable, ImportMixin):
  @property
  def is_num(self):
  - return any([t in self.type.upper() for t in self.num_types])
  + return (
  + self.type and
  + any([t in self.type.upper() for t in self.num_types])
  + )
  @property
  def is_time(self):
  - return any([t in self.type.upper() for t in self.date_types])
  + return (
  + self.type and
  + any([t in self.type.upper() for t in self.date_types])
  + )
  @property
  def is_string(self):
  - return any([t in self.type.upper() for t in self.str_types])
  + return (
  + self.type and
  + any([t in self.type.upper() for t in self.str_types])
  + )
  class BaseMetric(AuditMixinNullable, ImportMixin):
  