Issue with Empty Non-Main Nodes in Interface Mode of 'nav' Implementation

[alessandrocarminati]

In the current implementation, the nav interface mode displays non-main nodes as empty, without any captions.
This issue seems to stem from a problem in the graphviz-go implementation, as the desired output is achieved when using the dot interpreter in the distribution.
Upon reviewing the go-graphviz issues on GitHub, it appears to be related to the problem described in that particular issue.