add bic as required if private payer

fet2020/finance/forms.py

@@ -118,6 +118,7 @@ class BillCreateForm(forms.ModelForm):
         payer = cleaned_data.get("payer")
         name = cleaned_data.get("name_text")
         iban = cleaned_data.get("iban_text")
+        bic = cleaned_data.get("bic_text")
         saving = cleaned_data.get("saving")
 
         only_digital = cleaned_data.get("only_digital")
@@ -143,9 +144,10 @@ class BillCreateForm(forms.ModelForm):
         """
 
         if payer == Bill.Payer.ME:
-            if name == "" or iban == "":
+            if name == "" or iban == "" or bic == "":
                 raise ValidationError(
-                    f"Bankdaten unvollständig (Kontoinhaber: {name}, IBAN: {iban})."
+                    f"Bankdaten bei privater Bezahlung unvollständig. (Kontoinhaber:in: '{name}', "
+                    f"IBAN: '{iban}', BIC: '{bic}')."
                 )
 
         if payer == Bill.Payer.VEREIN or saving is not True: