Fatal error on external service configuration

[dasistwas]

How to reproduce:

1. Go to plugins -> Web services -> external services
2. Add a new external service
3. On the next page click on add functions

result is this fatal error:

Coding error detected, it must be fixed by a programmer: Cannot find file [dirroot]/mod/datalynx/externallib.php with external function implementation

More information about this error
Debug info:
Error code: codingerror
Stack trace:

    line 87 of /lib/externallib.php: coding_exception thrown
    line 199 of /admin/webservice/forms.php: call to external_api::external_function_info()
    line 214 of /lib/formslib.php: call to external_service_functions_form->definition()
    line 60 of /admin/webservice/service_functions.php: call to moodleform->__construct()

[michaelpollak]

Done some testing, looks good here :) Please confirm if you have time, thank you.