File "D:\PycharmProjects\smsenv\lib\site-packages\django\db\models\fields\related_descriptors.py", line 421, in __get__
    raise self.RelatedObjectDoesNotExist(
master.models.corporation.Corporation.supplier.RelatedObjectDoesNotExist: Corporation has no supplier.

corporation:Corporation = Corporation.objects.get(pk=1)
supplier = corporation.supplier    # OneToOneField，supplier未登录时，出错
# 使用 supplier前，需要判定其是否存在

if not hasattr(corporation, 'supplier'):
    raise SuspiciousOperation("仕入先見つかりません")

或者
if hasattr(corporation, 'supplier'):
    #後続処理
    pass

class Corporation(BaseModel):
    corporation_code = models.CharField(max_length=8, primary_key=True, verbose_name='法人コード')
    ・・・
class Supplier(BaseModel):
    corporation = models.OneToOneField(Corporation, on_delete=models.CASCADE, primary_key=True, verbose_name='法人コード')
    ・・・