Decimals was renamed to Precision in tdewolff/minify v2.7.0:
tdewolff/minify@2fed440
We accommodated that change here:
e3ca134#diff-50afd03ceba68ec4aeb65a643fe7e5a63c2953e33cae5190a8b57cc8214de78dR106
But we inadvertently used the singular form (decimal) instead of the plural form (decimals).