It seems that you encountered an error while running the ng serve command after upgrading Angular to the latest version. The error message read: "Error: Schema validation failed with the following errors: Data path "" must NOT have additional properties (sourceMap)."You mentioned that you found that the issue was with the additional property of sourceMap and removed it to resolve the issue. However, when attempting to uninstall and reinstall node modules, the error persisted. It's possible that there are other issues causing this error. You can try running npm cache clean --force and then npm install to see if it resolves the issue. If not, you can try deleting the node_modules folder and then running npm install again.I hope this helps! Let me know if you have any other questions.

It looks like you might be using a version of RxJS that is not compatible with the latest version of Angular. The error message you provided indicates that the schema validation failed and that there is an issue with the sourceMap property. One potential solution is to update RxJS to a version that is compatible with your version of Angular. You can check the Angular documentation to see which version of RxJS is recommended for your version of Angular. To update RxJS, you can use the following command:

Make sure to replace with the appropriate version number. If updating RxJS doesn't solve the issue, you may need to check your code for any syntax errors or other issues that could be causing the problem. Additionally, you could try deleting the node_modules folder and reinstalling all of your dependencies with the following commands:

Hopefully this will help you resolve the issue and get your project up and running again!