Resolving the issue “Invalid SharePoint App Package. Error: Part URI is not valid per rules defined in the Open Packaging Conventions specification” seems to have a lot to do with the code’s working directory structure.

SharePoint Online | O365 | Azure | + legacy & productivity
Resolving the issue “Invalid SharePoint App Package. Error: Part URI is not valid per rules defined in the Open Packaging Conventions specification” seems to have a lot to do with the code’s working directory structure.