Merge pull request #114 from Kerollmops/hot-fix-ranked-attribute

Do not error when an attribute is registered for ranking

src/rank/criterion/sort_by_attr.rs

@@ -78,7 +78,7 @@ impl<'a> SortByAttr<'a> {
             None => return Err(SortByAttrError::AttributeNotFound),
         };
 
-        if schema.props(attr).is_ranked() {
+        if !schema.props(attr).is_ranked() {
             return Err(SortByAttrError::AttributeNotRegisteredForRanking);
         }