Create user flow for broken projects

[atjn]

If a project is loaded with errors such as

• the system is referencing a component that does not exist
• there are more than one edge with the same id
• parts of a project cannot be parsed

...then the entire project just fails to load. A better solution would be to create popup windows for all these issues, that would allow the user to remediate. For example by creating the missing component, or by connecting it to an existing one.