Recently, we found out Mentee overview module is failing (T372164), because it makes invalid requests. The API response was this:
```
{
"error": "parameter-validation-failed",
"name": "activedaysago",
"value": "",
"failureCode": "badinteger",
"failureData": null,
"errorKey": "badinteger",
"messageTranslations": {
"cs": "Invalid value \"\" for integer parameter \"activedaysago\".",
"en": "Invalid value \"\" for integer parameter \"activedaysago\"."
},
"httpCode": 400,
"httpReason": "Bad Request"
}
```
and it was occuring in the default view (without setting any filters). To avoid any future #regression, we should improve our testing suite to verify Mentee overview is making valid API requests, at least in the default window.
This regression was introduced in [1057374: build: Update eslint-config-wikimedia to 0.28.2](https://gerrit.wikimedia.org/r/c/mediawiki/extensions/GrowthExperiments/+/1057374), which changed `$.extend` to `Object.assign` (which handle `undefined` values differently). Within this task, we should ensure MenteeOverviewApi gets a response when `undefined` is passed to `MenteeOverviewApi.setFilters` as a value.