### 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_
Key="index.html",
            Body="index",
            ContentType="text/html",
            ACL="public-read",
        )
        redirected_bucket_website = _website_bucket_url(bucket_name_redirected)
        response_no_redirect = .get(redirected_bucket_website, allow_redirects=False)
        assert response_no_redirect.status_code == 301
        assert response_no_redirect.content == b""
        response_redirected = .get(redirected_bucket_website)
        assert response_redirected.status_code == 200
        assert response_redirected.content == b"index"
        response = .get(bucket_website_url)
        assert response.status_code == 200
        assert response.content == b"index"
        assert response.content == response_redirected.content
        response_redirected = .get(f"{redirected_bucket_website}/random-key")
        assert response_redirected.status_code == 404
    @staticmethod
    def _get_static_hosting_transformers(snapshot):
        return [
            snapshot.transform.regex(
                "RequestId: (.*?)</li>", replacement="RequestId: <request-id></li>"
            ),
            snapshot.transform.regex("HostId: (.*?)</li>", replacement="HostId: <host-id></li>"),
            snapshot.transform.regex(
                "BucketName: (.*?)</li>", replacement="BucketName: <bucket-name></li>"
            ),
        ]
class TestS3Routing: