Circulation Rules Editor - Unexpected errors when modifying rules

Attempted to modify the circulation rules to transform an existing/saved nested rule into a single-line rule using the same parameters and policy associations. As the resulting error seemed to relate to the top line:
priority: criterium(t, g, m, s, c, b, a ), number-of-criteria, last-line

I attempted to modify the line to match the default syntax on http://folio-testing.aws.indexdata.com:
priority: t, g, m, s, c, b, a

Each attempt threw a different error (see attached)