unknown keyword "errorMessage"

Schemas using "errorMessage" or "message" keywords fail validation/compilation with the above error. Of course you can get past it by disabling strict mode (`--strict=false`), but it seems like you shouldn't have to give up strict mode to make it accept valid keywords. I tried `-c ajv-errors` to no avail.

Am I missing something obvious, or does the CLI just not have any way of loading the ajv-errors package (or others)?