fix(mdx-loader): loader error message should display stacktrace if no extra MDX details

[slorber]

Motivation

When MDX throws a regular JS error without extra useful attributes, the error message is not really helpful because the stacktrace is not included.

In these cases we want the stacktrace to be printed as well to troubleshoot the problem.

Note, for now this only works in the Webpack dev server:

The console (start+build) will print an unhelpful stacktrace:

This is very likely related to this issue: #9023

Test Plan

local only 😓

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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 88	🟢 97	🟢 92	🟢 100	🟠 89	Report
/docs/installation	🟠 71	🟢 100	🟢 92	🟢 100	🟠 89	Report

[github-actions]

Size Change: 0 B

Total Size: 1.1 MB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	117 kB
website/build/assets/css/styles.********.css	113 kB
website/build/assets/js/main.********.js	828 kB
website/build/index.html	41 kB

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