Investigate node colouring edge cases

[pdrieger]

In certain situations nodes get coloured if source colour and destination color is different for the same node Id which causes wrong display results in the visualisation. Create a simple reproducible set to validate and investigate this behaviour to find out what fixes or workaround can help in this situation.

[edro15]

@pdrieger I think this was actually fixed in #40 .. could you please confirm that's the case? 🙏