Dashboard chart of method coverage fails on mouse hover

[mytskine]

When moving the mouse over a point of the scatter chart of methods, nothing happens with Chromium 134. For each hovering, the JavaScript console displays a unhelpful error deep into nv.d3.min.js. The behavior is the same with Firefox ESR 128.9.

At a time, both scatter charts were broken, as reported in #440. The first chart (classes) was fixed but the second one (methods) was not, as someone reported in the same issue (after it was closed).

Since the class and method charts are similar, I supposed the browser, the bug was in the library used to build the SVG charts. Unfortunately, nvd3's last release was in 2017. It's a layer above d3js, but no longer compatible with recent releases of d3js. I'll submit a merge request that replaces nvd3 with a maintained library.

[sebastianbergmann]

I'll submit a merge request that replaces nvd3 with a maintained library.

Thank you!