Fix getWith should always return array.

Not sure about the fist check, I think we could check against `null` instead, but this way the previous behavior is preserved.

Author: sfadschm

src/Traits/ModelTrait.php

@@ -82,7 +82,18 @@ public function without($tables)
 	 */
 	protected function getWith(): array
 	{
-		return empty($this->with) ? [] : $this->with;
+		// Ensure $this->with is set at all
+		if(empty($this->with)){
+			$this->with = [];
+		}
+		
+		// Force a single table name into an array
+		if (!is_array($this->with))
+		{
+			$this->with = [$this->with];
+		}
+
+		return $this->with;
 	}
 
 	/**