### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

- Localstack fails with HTTP 500, error code "InternalError", message "not enough values to unpack (expected 2, got 1)" when `CopySource` is an invalid string for `copy_object` API.

### Expected Behavior

- For the same API `copy_object`, the cloud fails with HTTP 400, error code "InvalidArgument".
- Localstack should handle invalid `CopySource` i.e., it is a dictionary with one value or an invalid string not adhering to "{bucket}/{key}" format.

### How are you starting LocalStack?

With a `docker run` command

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    docker run localstack/localstack

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

    botoclient.copy_object(CopySource="Invalid_random_string", Bucket="test_bucket", Key=key) 


 test_bucket is a valid bucket.  

### Environment

```markdown
- OS: Ubuntu 22.04.2 LTS
- LocalStack: 2.1.0
- boto3: 1.28.6
```


### Anything else?

_No response_
CreateBucketConfiguration={"LocationConstraint": region_2}
        )
        target_bucket = s3_create_bucket(CreateBucketConfiguration={"LocationConstraint": region_3})
        with pytest.raises(ClientError) as e:
            bucket_logging_status = {
                "LoggingEnabled": {
                    "TargetBucket": target_bucket,
                    "TargetPrefix": "log",
                },
            }
            client.put_bucket_logging(
                Bucket=bucket_name_region_1, BucketLoggingStatus=bucket_logging_status
            )
        snapshot.match("put-bucket-logging-cross-us-east-1", e.value.response)
        with pytest.raises(ClientError) as e:
            bucket_logging_status = {
                "LoggingEnabled": {
                    "TargetBucket": target_bucket,
                    "TargetPrefix": "log",
                },
            }
            aws_client.s3.put_bucket_logging(
                Bucket=bucket_name_region_2, BucketLoggingStatus=bucket_logging_status
            )
        snapshot.match("put-bucket-logging-different-regions", e.value.response)
# TODO: maybe we can fake the IAM role as it's not needed in LocalStack
@pytest.mark.skipif(condition=TEST_S3_IMAGE, reason="IAM not enabled in S3 image")
class TestS3BucketReplication:
    @markers.aws.validated
    def test_replication_config_without_filter(