Plugin error from mmvec: index 0 is out of bounds for axis 0 with size 0

There is an error showcasing issues plotting the conditional probability heatmap

See below fore more details
https://forum.qiime2.org/t/plugin-error-from-mmvec-index-0-is-out-of-bounds-for-axis-0-with-size-0/23297

Start with the linked forum report and reproduce the conditional probability heatmap plotting error in mmvec. The payload names no source file or test, so locate the plotting entry point from the report and confirm the failing input. Done means the heatmap renders without the reported index-out-of-bounds error.

Written by the indexing model from the issue text.