Add error check to freesasa_export_tree()
Add error check to freesasa_export_tree()

JoaoRodrigues/freesasa,mittinatten/freesasa,mittinatten/freesasa,mittinatten/freesasa,JoaoRodrigues/freesasa,JoaoRodrigues/freesasa,JoaoRodrigues/freesasa,mittinatten/freesasa