Tentatively reword exception
Tentatively reword exception

We may still want to split this out into its own type if more
descriptive text is required (ie. mentioning Transforms of Children as
the target of mutation).

ppy/osu-framework,ppy/osu-framework,ppy/osu-framework,peppy/osu-framework,peppy/osu-framework,ZLima12/osu-framework,ZLima12/osu-framework,peppy/osu-framework,smoogipooo/osu-framework,smoogipooo/osu-framework