Strange error when saving from Developer Console

This post is more of a reference for future if I encounter this error again, but I had a rather strange error when trying to save a modification to a Apex class from Developer Console:

Failed to create createContainerMember for containerId=undefined: null is not a valid containerId

After some googling, I had found following help article indicating that you need to create a new workspace when this error appears.  This did fix my error, but it doesn't really explain why this error appears.  If you have more in-depth explanation as to why this would happen, let me know.