implemented moving of document positions

frontend/src/routes/document/View.svelte

@@ -22,6 +22,7 @@
         const resp = await fetch(url,{credentials:'include'});
         if (resp.ok){
             doc = await resp.json();
+            error = null;
         } else {
             error = await resp.text();
         }
@@ -72,6 +73,7 @@
         });
         if (resp.ok){
             doc.positions = await resp.json();
+            error = null;
         } else {
             error = await resp.text();
         }
@@ -189,7 +191,7 @@
             <button onclick={() => position_select = true}>{t('document.add_position')}</button>
             {/if}
         </legend>
-        <PositionList bind:document={doc} {submit} />
+        <PositionList bind:document={doc} {submit} bind:error={error} />
     </fieldset>
     <fieldset>
         <legend>{t('document.footer')}</legend>