Fix for uncatchable AbortErrors

Patching `window.fetch` without handling the `AbortError` results in
JS code that uses fetch, becoming unable to catch these errors. As such,
application errors will be emitted to the console (and in the case of
webpack-dev-server, to the browser window), that are very mysterious.
Even if one has try/catch blocks within an async function, or then/catch
blocks for the Promise using `fetch()`, these errors will not be
catched.

I am not fully in the know as to why it works this way (the internals of
an async/Promise are very convoluted especially when `this` is involved
as in here), but I suspect the patched call will emit its own
`AbortError` extra to the one that comes from the original one, and the
uncatched one in the patched function will resurface even after catching
one of them.

Author: karolyi

debug_toolbar/static/debug_toolbar/js/toolbar.js

@@ -329,6 +329,9 @@ const djdt = {
                 // Don't resolve the response via .json(). Instead
                 // continue to return it to allow the caller to consume as needed.
                 return response;
+            }).catch((err) => {
+                if (err.name === 'AbortError') return
+                throw(e);
             });
             return promise;
         };