# Steps to reproduce

* Start `localstack` (version 0.10.3).
* Don't create any lambda functions.
* Run:

```sh
AWS_ACCESS_KEY_ID='a' AWS_SECRET_ACCESS_KEY='b' \
aws lambda invoke \
  --function-name 'my-func' \
  --qualifier='qual' \
  --endpoint http://localhost:4574 test.out
```

* Expected behaviour — a `ResourceNotFoundException` from `aws-cli`.
* Actual behaviour — `An error occurred (500) when calling the Invoke operation` message and a 500 response.

This bug only appears if a `qualifier` is included in the request.
delimiter = '.'
    if runtime.startswith(LAMBDA_RUNTIME_NODEJS):
        file_ext = '.js'
    elif runtime.startswith(LAMBDA_RUNTIME_GOLANG):
        file_ext = ''
    elif runtime.startswith(LAMBDA_RUNTIME_DOTNETCORE2) or runtime.startswith(LAMBDA_RUNTIME_DOTNETCORE21):
        file_ext = '.dll'
        delimiter = ':'
    elif runtime.startswith(LAMBDA_RUNTIME_RUBY):
        file_ext = '.rb'
    elif runtime.startswith(LAMBDA_RUNTIME_CUSTOM_RUNTIME):
        file_ext = '.sh'
    else:
        file_ext = '.py'
    return '%s%s' % (handler_name.split(delimiter)[0], file_ext)
def get_handler_function_from_name(handler_name, runtime=LAMBDA_DEFAULT_RUNTIME):