BREAKING Case with no charge (#99)

When parsing a CAMT.054 file, setTotalChargesAndTaxAmount is only called when a "Chrgs" record exists. Therefore, getTotalChargesAndTaxAmount must allow to return NULL.

If you rely on this method, you must check for `NULL` value yourself.

src/DTO/Charges.php

@@ -18,7 +18,7 @@ class Charges
      */
     private $records = [];
 
-    public function getTotalChargesAndTaxAmount(): Money
+    public function getTotalChargesAndTaxAmount(): ?Money
     {
         return $this->totalChargesAndTaxAmount;
     }