Fix

assets/boot.html

@@ -32,7 +32,11 @@
 
 <main class="boot container py-5 text-center">
   <div class="spinner-border text-secondary mb-3" role="status" aria-hidden="true"></div>
-  <p id="boot-status" class="text-body-secondary">Preparing the offline copy…</p>
+  <!-- Empty until there is something to say. This page is on screen for a
+       moment on a first visit and then never again, and a line naming what it
+       is doing is a line nobody needs to read: the spinner already says wait.
+       It is here, and empty, because it is where fail() writes. -->
+  <p id="boot-status" class="text-body-secondary"></p>
   <noscript><p class="alert alert-warning d-inline-block">This app builds its
     pages on the device and needs JavaScript.</p></noscript>
 </main>
@@ -59,7 +63,7 @@
   }
 
   function start() {
-    if (tries >= 2) return fail('The offline copy could not start.');
+    if (tries >= 2) return fail('Setup could not finish.');
     try { sessionStorage.setItem('boot:tries', String(tries + 1)); } catch (err) {}
 
     navigator.serviceWorker.register('sw.js').then(function (registration) {
@@ -67,12 +71,12 @@
       // controlled yet. Otherwise wait for the one installing to get there.
       if (registration.active) return go();
       var worker = registration.installing || registration.waiting;
-      if (!worker) return fail('The offline copy did not install.');
+      if (!worker) return fail('Setup did not start.');
       worker.addEventListener('statechange', function (event) {
         if (event.target.state === 'activated') go();
       });
     }, function (err) {
-      fail('Could not install the offline copy: ' + err.message);
+      fail('Setup failed: ' + err.message);
     });
   }
 
@@ -86,7 +90,7 @@
   }
 
   if ('serviceWorker' in navigator) start();
-  else fail('This browser has no service worker support.');
+  else fail('Setup needs service workers, which this browser does not have.');
 })();
 </script>
 </body>