Change a console.warn to console.error for reporting bad rule insertion attempt in speedy mode

[Andarist]

I don't think this deserves a changeset, just a small unification as we use console.error for most of the warnings/errors reported.

[changeset-bot]

💥 No Changeset

Latest commit: 52da006

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[codecov]

Codecov Report

Merging #1811 into next will not change coverage.
The diff coverage is 100%.

Impacted Files	Coverage Δ
packages/sheet/src/index.js	100% <100%> (ø)	⬆️