### 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_
completed_ = aws_client.s3.get_(Bucket=s3_bucket, Key=key_name)
        assert completed_["Body"].read() == to_bytes(body)
    @markers.aws.only_localstack
    @pytest.mark.skipif(
        reason="Not implemented in other providers than v3, moto fails at decoding",
        condition=LEGACY_V2_S3_PROVIDER,
    )
    def test_put__chunked_newlines_no_sig(self, s3_bucket, aws_client, region_name):
        _key = "data"
        body = "test;test;test\r\ntest1;test1;test1\r\n"
        headers = {
            "Authorization": mock_aws_request_headers(
                "s3", aws_access_key_id=TEST_AWS_ACCESS_KEY_ID, region_name=region_name
            )["Authorization"],
            "Content-Type": "audio/mpeg",
            "X-Amz-Date": "20190918T051509Z",
            "X-Amz-Decoded-Content-Length": str(len(body)),
            "Content-Encoding": "aws-chunked",
        }
        data = "23\r\n" f"{body}\r\n" "0\r\n" "x-amz-checksum-crc32:AKHICA==\r\n" "\r\n"
        # put 
        url = f"{config.internal_service_url()}/{s3_bucket}/{_key}"
        .put(url, data, headers=headers, verify=False)
        # get 
        downloaded_ = aws_client.s3.get_(Bucket=s3_bucket, Key=_key)
        download_file_ = to_str(downloaded_["Body"].read())
        assert len(body) == len(str(download_file_))
        assert body == str(download_file_)
    @markers.aws.only_localstack
    def test_virtual_host_proxy_does_not_decode_gzip(self, aws_client, s3_bucket):