mod_rest: Improve error handling during format mapping Prevents e.g. a nil, error return going directly into e.g. json encoding, resulting in "null" being returned. Further handling improvements down the line is needed.

2c07bcf56a36d6e74dc0f5422e89bd61f4d31239 0.8-diverge
1656d4fd71d07aa3a52da89d4daf7723a555e7dd last-google-code-commit