Fixes account deletion with deductions

* adds a warning on removing an eco account if there are still deductions
    * this way a user needs to get rid of these deductions first

compensation/forms/eco_account.py

@@ -14,6 +14,7 @@ from compensation.forms.mixins import CompensationResponsibleFormMixin, PikCompe
 from compensation.models import EcoAccount
 from intervention.models import Handler, Responsibility, Legal
 from konova.forms import SimpleGeomForm
+from konova.forms.modals import RemoveModalForm
 from user.models import User, UserActionLogEntry
 
 
@@ -210,3 +211,16 @@ class EditEcoAccountForm(NewEcoAccountForm):
             # Add the log entry to the main objects log list
             self.instance.log.add(action)
         return self.instance
+
+
+class RemoveEcoAccountModalForm(RemoveModalForm):
+
+    def is_valid(self):
+        super_valid = super().is_valid()
+        has_deductions = self.instance.deductions.exists()
+        if has_deductions:
+            self.add_error(
+                "confirm",
+                _("The account can not be removed, since there are still deductions.")
+            )
+        return super_valid and not has_deductions