show key name when map value is of wrong type
Test Plan:
before:
$ arc lint Exception Error in parsing '.arclint' file, for linter 'Anonymizable fields'. Parameter has invalid type. Expected a regular expression, but value is not valid: preg_match(): Delimiter must not be alphanumeric or backslash (Run with `--trace` for a full exception trace.)
after:
$ arc lint Exception Error in parsing '.arclint' file, for linter 'Anonymizable fields'. Parameter 'script-and-regex.regex' has invalid type. Expected a regular expression, but value is not valid: preg_match(): Delimiter must not be alphanumeric or backslash (Run with `--trace` for a full exception trace.)
Reviewers: joshuaspence, epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: eadler, epriestley, Korvin
Differential Revision: https://secure.phabricator.com/D13458