Better error message when property unmarshalling failure

Author: fxaguessy

graph/rdf.go

@@ -33,7 +33,7 @@ func getPropertyValue(gph tstore.RDFGraph, propObj tstore.Object, prop string) (
 	case definedBy == rdf.RdfsClass, dataType == rdf.RdfsClass:
 		id, ok := propObj.Resource()
 		if !ok {
-			return nil, fmt.Errorf("get property '%s': object not resource identifier", prop)
+			return nil, fmt.Errorf("get property '%s': '%+v' object not resource identifier", prop, propObj)
 		}
 		return id, nil
 	case definedBy == rdf.RdfsList && dataType == rdf.NetRoute:

graph/resource.go

@@ -275,7 +275,7 @@ func (res *Resource) unmarshalFullRdf(gph tstore.RDFGraph) error {
 		}
 		propVal, err := getPropertyValue(gph, t.Object(), pred)
 		if err != nil {
-			return fmt.Errorf("unmarshalling property %s: val: %s", propKey, err)
+			return fmt.Errorf("unmarshalling property '%s' of resource '%s': %s", propKey, res.Id(), err)
 		}
 		if rdf.Properties.IsRDFList(pred) {
 			dataType, err := rdf.Properties.GetDataType(pred)