Added a check for sub-1€ donations

app/controller/campaign.php

@@ -86,6 +86,12 @@ class Campaign extends Controller
             $sum = $f3->get('amount_other');
         }
 
+        // If the donation is not a positive amount, we fail the donation.
+        if ($f3->get('amount') < 1) {
+            $f3->set("error", _("Montant du don invalide, il doit être supérieur à 1€."));
+            $f3->error("403");
+        }
+
         $f3->set('amount', $sum);
 
         $status = 0;