Improve currency code validation

apps/api/src/validators/is-currency-code.ts

@@ -25,19 +25,20 @@ export class IsExtendedCurrencyConstraint
   implements ValidatorConstraintInterface
 {
   public defaultMessage() {
-    return '$value must be a valid ISO4217 currency code';
+    return '$property must be a valid ISO4217 currency code';
   }
 
   public validate(currency: any) {
     // Return true if currency is a standard ISO 4217 code or a derived currency
     return (
-      isISO4217CurrencyCode(currency) ||
+      /^[A-Z]+$/.test(currency) &&
+      (isISO4217CurrencyCode(currency) ||
         [
           ...DERIVED_CURRENCIES.map((derivedCurrency) => {
             return derivedCurrency.currency;
           }),
           'USX'
-      ].includes(currency)
+        ].includes(currency))
     );
   }
 }