As reported by jmeuriss in MDLQA-13390:

getting an "invalid parameter exception" at step 6 of Test 2 when dismissing the modal showing the details of the competencies. The error doesn't occur when viewing dismissing the first modal window, but occurs with all the following ones. That is I view A2, dismiss the modal --> ok; I view B1 and dismiss the modal --> exception; I view B2 and dismiss the modal --> exception

Could be reproduced on QA test site with the following steps.

1. Log in as teacher and select a course
2. Go to the competencies page and add a competency to the course
3. Go to competency breakdown page 
4. Click a first time on "not rated" in Rating column then dismiss the modal --> ok
5. Click a second time on "not rated" then dismiss the modal --> exception thrown

Invalid parameter value detected
File: /lib/externallib.php
Line: 349

Stack trace:
moduleid => Invalid parameter value detected (Invalid external api parameter: the value is "", the server was expecting "int" type): Invalid external api parameter: the value is "", the server was expecting "int" type
Error code: invalidparameter

• line 349 of /lib/externallib.php: invalid_parameter_exception thrown
• line 223 of /lib/externallib.php: call to external_api::validate_parameters()
• line 59 of /lib/ajax/service.php: call to external_api::call_external_function()