After installing the extension, I entered "bigUML: New Empty UML Diagram" in a hurry without an open vscode workspace. VSCode doesn't handle this then through the extension and the file dialogue opens to create a new file with this (useless) filename. Then I chose some other name and thereby didn't create the uml file by using the extension.
We need to verify that a workspace is open before we allow creating new files.
Follow up #170
We need to verify that a workspace is open before we allow creating new files.