### 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_
)
        with pytest.raises(ClientError) as e:
            aws_client.s3.get_(Bucket=bucket_name, Key=_key)
        snapshot.match("get--invalid-state", e.value.response)
        snapshot.match("get__invalid_state", e.value.response)
        response = aws_client.s3.restore_(
            Bucket=bucket_name,
            Key=_key,
            RestoreRequest={
                "Days": 30,
                "GlacierJobParameters": {
                    "Tier": "Bulk",
                },
            },
        )
        snapshot.match("restore_", response)
        # AWS 
        response = aws_client.s3.head_(Bucket=bucket_name, Key=_key)
        if 'ongoing-request="false"' in response.get("Restore", ""):
            # if t
            restore_bucket_name = f"bucket-{short_uid()}"
            s3_create_bucket(Bucket=restore_bucket_name)
            aws_client.s3.copy_(
                CopySource={"Bucket": bucket_name, "Key": _key},
                Bucket=restore_bucket_name,
                Key=_key,
            )
            response = aws_client.s3.get_(Bucket=restore_bucket_name, Key=_key)
            assert "etag" in response.get("ResponseMetadata").get("HTTPHeaders")
class TestS3StaticWebsiteHosting: