Part icon is missing in ols4 hierarchy widget

[rombaum]

The p in the ols4 based hierarchy widget is missing in our widget.

I used milk from the ontology uberon as an example and saw that the p is missing in the hierarchy.

It is working for the hierarchy at the instance of EMBL-EBI: https://www.ebi.ac.uk/ols4/ontologies/uberon/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FUBERON_0001913

[VincentKneip]

The p icon is an SVG-image called part.svg, which should be provided at "{process.env.PUBLIC_URL!}/part.svg" (see here).
At EMBL-EBI, there is a corresponding image provided at https://www.ebi.ac.uk/ols4/part.svg. However, for our project, process.env.PUBLIC_URL! does not seem to match "https://www.ebi.ac.uk/ols4/".

A quick fix would be to change the line inside EntityTree.tsx in the ols4-project mentioned above from
src={urlJoin(process.env.PUBLIC_URL!, "/part.svg")}
to
src={"https://www.ebi.ac.uk/ols4/part.svg"}