Static generation failures don't show cause chains

[arctic-hen7]

Describe the bug
If there's a failure in static generation, no error cause chain is shown, which makes debugging issues in complex pipelines very difficult, especially once custom plugins get involved.

To Reproduce
Steps to reproduce the behavior:
Gracefully return an error in any static generation function and observe that the cause chain is nowhere to be found.

Expected behavior
Cause chains should be displayed with fmterr.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• Perseus Version: v0.3.0
• Sycamore Version: v0.7.1
• OS: Ubuntu
• Browser: N/A
• Browser Version: N/A