### 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_
filter_key: str,
    filter_value: str | int | dict[str, str],
    object_key: ObjectKey,
    size: ObjectSize,
    object_tags: dict[str, str],
):
    match filter_key:
        case "Prefix":
            return object_key.startswith(filter_value)
        case "Tag":
            return object_tags and object_tags.get(filter_value.get("Key")) == filter_value.get(
                "Value"
            )
        case "ObjectSizeGreaterThan":
            return size > filter_value
        case "ObjectSizeLessThan":
            return size < filter_value
        case "Tags":  
            return object_tags and all(
                object_tags.get(tag.get("Key")) == tag.get("Value") for tag in filter_value
            )
def parse_expiration_header(