- Updated the error-handler to support Objection v2.x errors

- Updated package.json's engines.node to `>= 8`

Author: Dekel Barzilay

package.json

@@ -31,7 +31,7 @@
     "url": "https://github.com/feathersjs-ecosystem/feathers-objection/issues"
   },
   "engines": {
-    "node": ">= 6"
+    "node": ">= 8"
   },
   "main": "lib/",
   "types": "types",