Issue title: Mouse over sensor not existing error
 Issue body: I have a setup where I have a mouse over sensor connected to a script and i print the controller's sensors. It shows up except when I click, the sensor disappears completely from the cont.sensors list and I get an error. When i do not click, it re-appears. If you need a screenshot or .blend, I can provide one.
 Comments: 
 Comment 0: I don't know what happened but a re-install of UPBGE fixed it
{'source': 'GithubIssues', 'repo_name_with_owner': 'UPBGE/blender', 'issue_id': 266687921, 'repo_stars': 291.0}