### 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("put--match-both-rules", put_)
        get_ = aws_client.s3.get_(Bucket=s3_bucket, Key=key_match_1)
        snapshot.match("get--match-both-rules", get_)
        _, parsed_exp_rule = parse_expiration_header(put_["Expiration"])
        assert parsed_exp_rule == rule_id_1
        key_match_2 = "test-one-rule"
        tag_set_match_one = "testlifecycle=positive"
        put__2 = aws_client.s3.put_(
            Body=b"test", Bucket=s3_bucket, Key=key_match_2, Tagging=tag_set_match_one
        )
        snapshot.match("put--match-rule-1", put__2)
        get__2 = aws_client.s3.get_(Bucket=s3_bucket, Key=key_match_2)
        snapshot.match("get--match-rule-1", get__2)
        _, parsed_exp_rule = parse_expiration_header(put__2["Expiration"])
        assert parsed_exp_rule == rule_id_1
        key_no_match = "no-rules"
        tag_set_no_match = "testlifecycle2=positivetwo"
        put__3 = aws_client.s3.put_(
            Body=b"test", Bucket=s3_bucket, Key=key_no_match, Tagging=tag_set_no_match
        )
        snapshot.match("put--no-match", put__3)
        assert "Expiration" not in put__3
        get__3 = aws_client.s3.get_(Bucket=s3_bucket, Key=key_no_match)
        snapshot.match("get--no-match", get__3)
        key_no_tags = "no-tags"
        put__4 = aws_client.s3.put_(Body=b"test", Bucket=s3_bucket, Key=key_no_tags)
        snapshot.match("put--no-tags", put__4)
        assert "Expiration" not in put__4
        get__4 = aws_client.s3.get_(Bucket=s3_bucket, Key=key_no_tags)
        snapshot.match("get--no-tags", get__4)