Error Ledger.can_delete() did not return reason if delete allowed.

brewman/brewman/models/master.py

@@ -212,7 +212,7 @@ class LedgerBase(Base):
             return False, 'Account has journal entries'
         if len(self.products) > 0:
             return False, 'Account has products'
-        return True
+        return True, ''
 
     @classmethod
     def get_code(cls, type):