### 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_
)
        get_obj_non_versioned = aws_client.s3.get_(Bucket=s3_bucket, Key=key)
        snapshot.match("get-post-versioned", get_obj_non_versioned)
        # crea
        key_2 = "versioned-bucket-key"
        put_obj_versioned_1 = aws_client.s3.put_(
            Bucket=s3_bucket, Key=key_2, Body="versioned-key"
        )
        snapshot.match("put-obj-versioned-1", put_obj_versioned_1)
        put_obj_versioned_2 = aws_client.s3.put_(
            Bucket=s3_bucket, Key=key_2, Body="versioned-key-updated"
        )
        snapshot.match("put-obj-versioned-2", put_obj_versioned_2)
        get_obj_versioned = aws_client.s3.get_(Bucket=s3_bucket, Key=key_2)
        snapshot.match("get-obj-versioned", get_obj_versioned)
        list_obj_post_versioned = aws_client.s3.list__versions(Bucket=s3_bucket)
        snapshot.match("list--versioned", list_obj_post_versioned)
        # disa
        # all 
        aws_client.s3.put_bucket_versioning(
            Bucket=s3_bucket,
            VersioningConfiguration={"Status": "Suspended"},
        )
        list_obj_post_versioned_disabled = aws_client.s3.list__versions(Bucket=s3_bucket)
        snapshot.match("list-bucket-suspended", list_obj_post_versioned_disabled)
        get_obj_versioned_disabled = aws_client.s3.get_(Bucket=s3_bucket, Key=key_2)
        snapshot.match("get-obj-versioned-disabled", get_obj_versioned_disabled)
        get_obj_non_versioned_disabled = aws_client.s3.get_(Bucket=s3_bucket, Key=key)
        snapshot.match("get-obj-non-versioned-disabled", get_obj_non_versioned_disabled)
        # won'