Malformed XML when setting bucket lifecycle with Go SDK

I have been trying to use the Go SDK to put a lifecycle configuration for a bucket but I keep getting Malformed XML errors. This is the relevant section of the code:

	rule := types.LifecycleRule{
		Status: types.ExpirationStatusDisabled,
		ID:     aws.String("testid2"),
		NoncurrentVersionExpiration: &types.NoncurrentVersionExpiration{
			NewerNoncurrentVersions: 4,
			NoncurrentDays:          1,
		},
		Filter: filter,
	}
	bucketConfig := types.BucketLifecycleConfiguration{
		Rules: []types.LifecycleRule{rule},
	}
	putBucketConfigInput := &s3.PutBucketLifecycleConfigurationInput{
		Bucket:                 aws.String("beer-sample-default-default-test5"),
		LifecycleConfiguration: &bucketConfig,
	}

	bucketLifecycleOutput, err := client.PutBucketLifecycleConfiguration(aws.BackgroundContext(),
		putBucketConfigInput, func(*s3.Options) {})

Would love to get some idea on where I'm going wrong. Thanks!