fix: skip discounts with value 0€

src/Service/AccommodationBookingBreakdownCalculator.php

@@ -51,11 +51,14 @@ class AccommodationBookingBreakdownCalculator
         $discountSum = 0;
 
         foreach ($buckets as [$label, $percent, $base]) {
-            if (null === $percent) {
+            $amount = self::discountAmount($base, $percent);
+
+            // Nothing to show for a discount of 0 %, or one on a bucket this booking has no
+            // price in — a "– 0,00 €" row only raises questions.
+            if (0 === $amount) {
                 continue;
             }
 
-            $amount = self::discountAmount($base, $percent);
             $discountSum += $amount;
             $discounts[] = ['label' => $label, 'percent' => $percent, 'amount' => $amount];
         }