Revert "Selection: workaround for "Trying to get property of non-obje…

…ct", thx to @hranicka, partially closes #15"

This reverts commit 3c44de6.

src/Database/Table/Selection.php

@@ -972,10 +972,6 @@ public function offsetSet($key, $value)
 	public function offsetGet($key)
 	{
 		$this->execute();
-		if ($this->rows === NULL) {
-			$this->cache = NULL;
-			return $this->data[$key];
-		}
 		return $this->rows[$key];
 	}