refactor(services): Barcodes always accept strings

templates/contract/de.html

@@ -56,7 +56,7 @@
         </div>
         <div class="column">
           <img style="vertical-align: revert; margin-top: auto; object-fit: cover; max-height: 2cm;"
-            src="data:image/png;base64,{{ barcode .ID $.BarcodeFormat $.BarcodePrefix }}" />
+            src="data:image/png;base64,{{ barcode (printf "%d" .ID) $.BarcodeFormat $.BarcodePrefix }}" />
         </div>
       </div>
       <div class="columns" style="padding-top: 1rem;">