Handle error on Qualitative analysis

[EliotRagueneau]

Right now, if the submitted analysis contains error, the loader keeps loading forever. We need to display the error messages.

Also when no name is provided for the gene column, it creates an error without any message by sending empty dataset. We need to give a default name for the first column if some data is otherwise provided

[snehagahlot3]

Hi, I'm a GSoC 2026 applicant interested in the pathway visualization project. I noticed this issue while exploring the PathwayBrowser. I'd love to understand the expected behavior better — is this something that could be addressed as part of the GSoC project scope?