Removing, for now, the join table information when using 'matching'

Hydrating the join table with matching presents several challenges,
revisit this commit upon the first bug report asking for the extra table
info :)

src/ORM/Association/BelongsToMany.php

@@ -34,6 +34,7 @@ class BelongsToMany extends Association {
 	use ExternalAssociationTrait {
 		_options as _externalOptions;
 		_addFilteringCondition as _addExternalConditions;
+		transformRow as protected _transformRow;
 	}
 
 /**
@@ -243,6 +244,19 @@ public function attachTo(Query $query, array $options = []) {
 			->attachTo($query, $options);
 	}
 
+/**
+ * Correctly nests a result row associated values into the correct array keys inside the
+ * source results.
+ *
+ * @param array $row
+ * @return array
+ */
+	public function transformRow($row) {
+		$row = $this->_transformRow($row);
+		unset($row[$this->junction()->alias()]);
+		return $row;
+	}
+
 /**
  * Get the relationship type.
  *

src/ORM/ResultSet.php

@@ -398,6 +398,9 @@ protected function _groupResult($row) {
 		}
 
 		foreach($presentAliases as $alias => $present) {
+			if (!isset($results[$alias])) {
+				continue;
+			}
 			$results[$defaultAlias][$alias] = $results[$alias];
 		}