### 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_
snapshot.match("wrong-destination-format", e.value.response)
        # set 
        with pytest.raises(ClientError) as e:
            inv_config = _get_config()
            inv_config["Schedule"]["Frequency"] = "Hourly"
            _put_bucket_inventory_configuration(inv_config)
        snapshot.match("wrong-schedule-frequency", e.value.response)
        # set 
        with pytest.raises(ClientError) as e:
            inv_config = _get_config()
            inv_config["IncludedVersions"] = "Wrong"
            _put_bucket_inventory_configuration(inv_config)
        snapshot.match("wrong--versions", e.value.response)
        # set 
        with pytest.raises(ClientError) as e:
            inv_config = _get_config()
            inv_config["OptionalFields"] = ["TestField"]
            _put_bucket_inventory_configuration(inv_config)
        snapshot.match("wrong-optional-field", e.value.response)
    @markers.aws.validated
    def test_put_bucket_inventory_config_order(self, aws_client, s3_create_bucket, snapshot):
        snapshot.add_transformer(snapshot.transform.resource_name())
        src_bucket = s3_create_bucket()
        dest_bucket = s3_create_bucket()
        def _put_bucket_inventory_configuration(config_id: str):
            inventory_configuration = {
                "Id": config_id,
                "Destination": {
                    "S3BucketDestination": {
                        "Bucket": f"arn:aws:s3:::{dest_bucket}",