FIX: improve badge granter resilience (#37674)

Two issues were found in BadgeGranter that could prevent badges from
being granted.

First, `Array#compact!` returns `nil` when no elements are removed. For
PostAction triggers, `[post_id, related_post_id].compact!` returns `nil`
when `related_post_id` is present (nothing to compact), causing the
post_ids payload to be silently lost. Using `compact` instead always
returns the array.

Second, `process_queue!` had no error isolation between badges. A single
badge with a broken SQL query would raise an exception and abort
processing of all remaining badges in the queue. Since queue items are
already popped from Redis at that point, they are lost. Each badge is
now rescued individually so one failure doesn't block the rest.

https://meta.discourse.org/t/394444

app/services/badge_granter.rb

@@ -222,7 +222,7 @@ class BadgeGranter
       payload = { type: "TrustLevelChange", user_ids: [user.id] }
     when Badge::Trigger::PostAction
       action = opt[:post_action]
-      payload = { type: "PostAction", post_ids: [action.post_id, action.related_post_id].compact! }
+      payload = { type: "PostAction", post_ids: [action.post_id, action.related_post_id].compact }
     end
 
     Discourse.redis.lpush queue_key, payload.to_json if payload
@@ -248,7 +248,11 @@ class BadgeGranter
 
       next if post_ids.blank? && user_ids.blank?
 
-      find_by_type(type).each { |badge| backfill(badge, post_ids: post_ids, user_ids: user_ids) }
+      find_by_type(type).each do |badge|
+        backfill(badge, post_ids:, user_ids:)
+      rescue => e
+        Rails.logger.warn("Failed to backfill '#{badge.name}' badge: #{e.message}")
+      end
     end
   end
 

spec/services/badge_granter_spec.rb

@@ -572,6 +572,51 @@ RSpec.describe BadgeGranter do
     end
   end
 
+  describe ".queue_badge_grant" do
+    it "includes both post_id and related_post_id for PostAction triggers" do
+      post_action = Struct.new(:post_id, :related_post_id).new(1, 2)
+
+      BadgeGranter.queue_badge_grant(Badge::Trigger::PostAction, post_action:)
+      raw = Discourse.redis.lpop(BadgeGranter.queue_key)
+      parsed = JSON.parse(raw)
+
+      expect(parsed["post_ids"]).to contain_exactly(1, 2)
+    end
+  end
+
+  describe ".process_queue!" do
+    fab!(:user) { Fabricate(:user, refresh_auto_groups: true) }
+
+    it "continues processing other badges when one badge fails to backfill" do
+      query = <<~SQL
+        SELECT p.user_id, p.id post_id, p.updated_at granted_at
+        FROM badge_posts p
+        WHERE p.raw LIKE '%Give Me A Badge%'
+        AND (:backfill OR p.id IN (:post_ids))
+      SQL
+
+      broken_badge =
+        Fabricate(
+          :badge,
+          query: "broken",
+          trigger: Badge::Trigger::PostRevision,
+          target_posts: true,
+        )
+      good_badge =
+        Fabricate(:badge, query:, trigger: Badge::Trigger::PostRevision, target_posts: true)
+
+      create_post(user:, raw: "Give Me A Badge")
+
+      allow(BadgeGranter).to receive(:backfill).and_wrap_original do |method, badge, opts|
+        raise BadgeGranter::GrantError, "broken query" if badge.id == broken_badge.id
+        method.call(badge, opts)
+      end
+
+      expect { BadgeGranter.process_queue! }.not_to raise_error
+      expect(UserBadge.exists?(user:, badge: good_badge)).to eq(true)
+    end
+  end
+
   describe "update_badges" do
     fab!(:user) { Fabricate(:user, refresh_auto_groups: true) }
     fab!(:liker) { Fabricate(:user, refresh_auto_groups: true) }