You can try following steps:
1. The problem might have to do with the installation of MATLAB R2019a on to your machine. You can try a clean uninstall of MATLAB R2019a and then re-installing it again. Before uninstalling MATLAB, please deactivate the installation. Instructions on how to both deactivate and uninstall MATLAB on a macOS are described in this link. After following those steps, please also delete anything that references MathWorks or MATLAB from the following folders:
- ~/Library/Application Support
- ~/Library/Caches
- ~/Library/Containers
- ~/Library/Cookies
- ~/Library/LaunchAgents
- ~/Library/LaunchDaemons
- ~Library/Logs
- ~/Library/Preferences
- ~/Library/PreferencePanel
You can find these folders by navigating to Finder -> Go -> Go to Folder.
Then search "~/Library".
2. Once all of this is completed, please then try re-installing MATLAB R2019a.