Simplify json error reporting (#3286)

Json validation errors used to include the instance (the submitted
json), the schema and the error. This changes the reporting to only
print the error message without the schema and instance. This is a
temporary fix until this is implemented:
python-jsonschema/jsonschema#1218

It also standardizes the message for `FILE_COPY_STATUS` notifications,
opting for the less verbose version.

app/grandchallenge/components/tasks.py

@@ -1049,7 +1049,7 @@ def add_file_to_component_interface_value(
             civ.full_clean()
         except ValidationError as e:
             civ.delete()
-            error = str(e)
+            error = str(e.message)
         else:
             user_upload.copy_object(to_field=civ.file)
             civ.save()
@@ -1200,7 +1200,7 @@ def add_file_to_object(
             civ = ComponentInterfaceValue.objects.get(pk=civ_pk)
             object.values.remove(civ)
     except ValidationError as e:
-        error = str(e)
+        error = str(e.message)
 
     if error is not None:
         Notification.send(
@@ -1209,7 +1209,7 @@ def add_file_to_object(
             message=f"File for interface {interface.title} failed validation.",
             target=object.base_object,
             description=(
-                f"File for interface {interface.title} added to {object_pk} "
-                f"in {object.base_object.title} failed validation:\n{error}."
+                f"File for interface {interface.title} "
+                f"failed validation:\n{error}."
             ),
         )

app/grandchallenge/core/validators.py

@@ -161,7 +161,9 @@ def __call__(self, value):
         try:
             validate(value, self.schema, registry=self.registry)
         except JSONValidationError as e:
-            raise ValidationError(f"JSON does not fulfill schema: {e}")
+            raise ValidationError(
+                f"JSON does not fulfill schema: instance {e.message.replace(str(e.instance) + ' ', '')}"
+            )
 
     def __eq__(self, other):
         return isinstance(other, JSONValidator) and self.schema == other.schema

app/tests/components_tests/test_serializers.py

@@ -346,7 +346,7 @@ def test_civ_post_value_required(kind):
 
     # verify
     assert not serializer.is_valid()
-    assert "JSON does not fulfill schema: None is not of type" in str(
+    assert "JSON does not fulfill schema: instance is not of type" in str(
         serializer.errors["__all__"][0]
     )