schema.markSchemaErrorKey() disposes of oneOf context

[jordan-wu-97]

oneOf validation provides a good reason of value doesn't match any schema from "oneOf"

kin-openapi/openapi3/schema.go

Lines 1380 to 1381 in 9dbb4c3

	e.Origin = fmt.Errorf("doesn't match schema due to: %w", validationErrors)
	e.Reason = `value doesn't match any schema from "oneOf"`

However, the function markSchemaErrorKey unwraps the Origin to err, resulting in the original error containing the oneOf context being lost (line 2125)

kin-openapi/openapi3/schema.go

Lines 2121 to 2139 in 9dbb4c3

	func markSchemaErrorKey(err error, key string) error {
	var me multiErrorForOneOf
	if errors.As(err, &me) {
	err = me.Unwrap()
	}
	if v, ok := err.(*SchemaError); ok {
	v.reversePath = append(v.reversePath, key)
	return v
	}
	if v, ok := err.(MultiError); ok {
	for _, e := range v {
	_ = markSchemaErrorKey(e, key)
	}
	return v
	}
	return err
	}

Example:

func TestOneOfSchema(t *testing.T) {

	openapi3.SchemaErrorDetailsDisabled = true

	// language=json
	raw := `
{
	"foo": [ "bar" ]
}
`

	// language=json
	schema := `
{
	"type": "object",
	"properties": {
		"foo": {
			"oneOf": [
				{
					"type": "number"
				},
					{
					"type": "string"
				}
			]
		}
	}
}
`

	s := openapi3.NewSchema()
	err := s.UnmarshalJSON([]byte(schema))
	require.NoError(t, err)
	err = s.Validate(context.Background())
	require.NoError(t, err)

	obj := make(map[string]interface{})
	err = json.Unmarshal([]byte(raw), &obj)
	require.NoError(t, err)

	err = s.VisitJSON(obj, openapi3.MultiErrors())
	fmt.Println(err.Error())

}

Output:

Error at "/foo": value must be a number | Error at "/foo": value must be a string

We lost the error message describing that foo must be oneOf the schemas