### 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_
response = aws_client.s3.get_bucket_analytics_configuration(
            Bucket=bucket,
            Id=storage_analysis["Id"],
        )
        snapshot.match("get_config_with_storage_analysis_1", response)
        # upda
        storage_analysis["Filter"]["Prefix"] = "test_ls_2"
        aws_client.s3.put_bucket_analytics_configuration(
            Bucket=bucket,
            Id=storage_analysis["Id"],
            AnalyticsConfiguration=storage_analysis,
        )
        response = aws_client.s3.get_bucket_analytics_configuration(
            Bucket=bucket,
            Id=storage_analysis["Id"],
        )
        snapshot.match("get_config_with_storage_analysis_2", response)
        # add 
        storage_analysis["Id"] = "config_with_storage_analysis_2"
        storage_analysis["Filter"]["Prefix"] = "test_ls_3"
        aws_client.s3.put_bucket_analytics_configuration(
            Bucket=bucket, Id=storage_analysis["Id"], AnalyticsConfiguration=storage_analysis
        )
        response = aws_client.s3.get_bucket_analytics_configuration(
            Bucket=bucket,
            Id=storage_analysis["Id"],
        )
        snapshot.match("get_config_with_storage_analysis_3", response)
        response = aws_client.s3.list_bucket_analytics_configurations(Bucket=bucket)
        snapshot.match("list_config_with_storage_analysis_1", response)