Report every failed fetch instead of discarding it

Twenty-four fetch chains ended in an empty catch, which is not error handling
but error deletion: the request fails, nothing renders, nothing is logged, and
the surface sits on Loading forever. That is how the mesh chat's ReferenceError
read as a slow load for as long as it did.

Plugin/unraid/pages/rsync.php

@@ -1074,7 +1074,7 @@ function vvRyLoad() {
   fetch('/plugins/varaverk/api/rsync.php')
     .then(r => r.json())
     .then(_render)
-    .catch(() => {});
+    .catch(e => vvFetchErr('rsync config', e));
 }
 
 vvRyLoad();
@@ -1499,7 +1499,7 @@ function vvRpLoad() {
         _vvRpFillForm(_vvRpSelected);
       }
     })
-    .catch(() => {});
+    .catch(e => vvFetchErr('rsync profiles', e));
 }
 
 function _vvRpPopulateSelector() {
@@ -1656,7 +1656,7 @@ function vvMsStop() {
   fetch('/plugins/varaverk/api/manual_sync.php', { method: 'POST', body: fd })
     .then(r => r.json())
     .then(() => {})
-    .catch(() => {})
+    .catch(e => vvFetchErr('manual sync start', e))
     .finally(() => { btn.textContent = '■ Stop'; btn.disabled = false; });
 }
 
@@ -2018,7 +2018,7 @@ function _vvMsStartPoll(token, btn, stat, out, badge, stopBtn) {
           setTimeout(() => { badge.style.display = 'none'; stat.textContent = ''; }, 6000);
         }
       })
-      .catch(() => {});
+      .catch(e => vvFetchErr('manual sync poll', e));
   }, 1500);
 }
 
@@ -2039,7 +2039,7 @@ function vvMsLoadRecent() {
   fetch(_MS_API + '?action=recent')
     .then(r => r.json())
     .then(d => { _vvMsRecent = (d && d.rows) || []; _msRenderRecent(); })
-    .catch(() => {});
+    .catch(e => vvFetchErr('recent syncs', e));
 }
 
 function _msRenderRecent() {
@@ -2098,7 +2098,7 @@ document.addEventListener('click', async ev => {
     body: new URLSearchParams(body) })
     .then(r => r.json())
     .then(() => vvMsLoadRecent())
-    .catch(() => {});
+    .catch(e => vvFetchErr('manual sync action', e));
 });
 
 // Fills the form and stops. Deliberately does not run: one click away from a transfer that may