Issue 5549 - Implement missing error handlings for custom filter lists

messageResponder.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 251 matching lines @@
     return subscription.filters.map(convertFilter);
   });
 
   port.on("filters.importRaw", (message, sender) =>
   {
     let result = require("filterValidation").parseFilters(message.text);
     let errors = [];
     for (let error of result.errors)
     {
       if (error.type != "unexpected-filter-list-header")
-        errors.push(error.toString());
+      {
+        // passing along all the info available through the error object
+        // in case we'll ever need these extra info in the future
+        errors.push({

[saroyanm, 2018/01/29 11:44:48]

Detail: Why not just pass "error" Object ?
errors.push(error);

[a.giammarchi, 2018/01/29 17:36:32]

I've missed this: because it comes from a class unknown to the outer world. This
was actually Thomas hint on how this error should've passed and I agree it's
cleaner this way.

[saroyanm, 2018/01/30 12:03:44]

@Thomas, can you please let me know what is the reason of not passing actual
error Object ? Because from what I can see it's the only place where we are
exctracting data out of the object rather than passing the actual object.

[Thomas Greiner, 2018/01/30 13:08:59]

We can only pass plain objects using the messaging API:

"A message can contain any valid JSON object (null, boolean, number, string,
array, or object)."
Source: https://developer.chrome.com/apps/messaging

"An object that can be serialized to JSON."
Source:
https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/runtime/sendMes...

Alternatively, we may be able to extend the errors to expose a `toJSON()` method
but it's not clear whether Chrome uses it and it's probably best not to rely on
implementation details because it might differ for other browsers.
We're also converting `Subscription` and `Filter` objects (see
https://hg.adblockplus.org/adblockplusui/file/tip/messageResponder.js#l54).

@Andrea If you want you should be able to reuse the `convertObject()` function I
linked to above for converting errors.

+          lineno: error.lineno,
+          reason: error.reason,
+          type: error.type
+        });
+      }
     }
 
     if (errors.length > 0)
       return errors;
 
     let seenFilter = Object.create(null);
     for (let filter of result.filters)
     {
       FilterStorage.addFilter(filter);
       seenFilter[filter.text] = null;
@@ skipping 173 matching lines @@
     if (message.url)
       subscriptions = [Subscription.fromURL(message.url)];
 
     for (let subscription of subscriptions)
     {
       if (subscription instanceof DownloadableSubscription)
         Synchronizer.execute(subscription, true);
     }
   });
 })(this);