Do not retry aborted requests and always handle promise rejection

When a network request is aborted through an external signal, it does not make
any sense to retry it.

Also, pending request promises were being (correctly) rejected when the request
failed, but when no one was actually interested in that request, this means that
the rejected promise went unhandled, leading to Node.js issuing an
"UnhandledPromiseRejectionWarning" message to the console.

Author: tidoust

fetch-filecache.js

@@ -265,7 +265,7 @@ async function fetch(url, options) {
   }
 
   /**
-   * Create a pending fetch promise and keep controls over that promise so that
+   * Create a pending fetch promise and keep control over that promise so that
    * the code may resolve or reject it through calls to resolvePendingFetch and
    * rejectPendingFetch functions
    */
@@ -277,6 +277,11 @@ async function fetch(url, options) {
       reject = innerReject;
     });
     pendingFetches[url] = { promise, resolve, reject };
+
+    // Make sure that we catch rejection (in case no one is actually looking
+    // for this URL at the same time, otherwise Node.js will complain with an
+    // "UnhandledPromiseRejectionWarning" message)
+    promise.catch(err => {});
   }
 
   function resolvePendingFetch(url) {
@@ -376,10 +381,10 @@ async function fetch(url, options) {
         return await baseFetch(url, options);
       }
       catch (err) {
-        if (remainingAttempts <= 0) throw err;
+        if ((err.name === 'AbortError') || (remainingAttempts <= 0)) throw err;
         log('fetch attempt failed, sleep and try again');
         await sleep(2000 + Math.floor(Math.random() * 8000));
-        return fetchWithRetry(url, options, remainingAttempts - 1);
+        return await fetchWithRetry(url, options, remainingAttempts - 1);
       }
     }
 
@@ -409,7 +414,7 @@ async function fetch(url, options) {
         return response;
       }
       else {
-        resolvePendingFetch(url);
+        resolvePendingFetch(url, 'test');
         return readFromCache();
       }
     }