FIX: Allow invalid plural keys in MF translations

We can get translations with invalid plural keys from Crowdin
or from custom overrides. Currently, this will raise an error and the
locales won’t be outputted at all.

This patch addresses this issue by using the new `strict: false` option
of our `messageformat-wrapper` gem, allowing to generate locales even if
there are invalid plural keys present.

Gemfile.lock

@@ -236,7 +236,7 @@ GEM
     memory_profiler (1.0.2)
     message_bus (4.3.8)
       rack (>= 1.1.3)
-    messageformat-wrapper (1.0.0)
+    messageformat-wrapper (1.1.0)
       mini_racer (>= 0.6.3)
     method_source (1.1.0)
     mini_mime (1.1.5)

lib/js_locale_helper.rb

@@ -150,7 +150,7 @@ module JsLocaleHelper
           )
         end
         .compact_blank
-    compiled = MessageFormat.compile(message_formats.keys, message_formats)
+    compiled = MessageFormat.compile(message_formats.keys, message_formats, strict: false)
     transpiled = DiscourseJsProcessor.transpile(<<~JS, "", "discourse-mf")
       import Messages from '@messageformat/runtime/messages';
       #{compiled.sub("export default", "const msgData =")};

spec/lib/js_locale_helper_spec.rb

@@ -147,18 +147,34 @@ RSpec.describe JsLocaleHelper do
   end
 
   describe ".output_MF" do
-    let(:output) { described_class.output_MF(locale).gsub(/^import.*$/, "") }
-    let(:generated_locales) { v8_ctx.eval("Object.keys(I18n._mfMessages._data)") }
-    let(:translated_message) do
-      v8_ctx.eval("I18n._mfMessages.get('posts_likes_MF', {count: 3, ratio: 'med'})")
-    end
-    let!(:overriden_translation) do
+    fab!(:overriden_translation_en) do
       Fabricate(
         :translation_override,
         translation_key: "admin_js.admin.user.penalty_history_MF",
         value: "OVERRIDEN",
       )
     end
+    fab!(:overriden_translation_ja) do
+      Fabricate(
+        :translation_override,
+        locale: "ja",
+        translation_key: "js.posts_likes_MF",
+        value: "{ count, plural, one {返信 # 件、} other {返信 # 件、} }",
+      )
+    end
+    fab!(:overriden_translation_he) do
+      Fabricate(
+        :translation_override,
+        locale: "he",
+        translation_key: "js.posts_likes_MF",
+        value: "{ count, plural, ",
+      )
+    end
+    let(:output) { described_class.output_MF(locale).gsub(/^import.*$/, "") }
+    let(:generated_locales) { v8_ctx.eval("Object.keys(I18n._mfMessages._data)") }
+    let(:translated_message) do
+      v8_ctx.eval("I18n._mfMessages.get('posts_likes_MF', {count: 3, ratio: 'med'})")
+    end
 
     before { v8_ctx.eval(output) }
 
@@ -227,5 +243,21 @@ RSpec.describe JsLocaleHelper do
         end
       end
     end
+
+    context "when locale contains invalid plural keys" do
+      let(:locale) { "ja" }
+
+      it "does not raise an error" do
+        expect(generated_locales).to match(%w[ja en])
+      end
+    end
+
+    context "when locale contains malformed messages" do
+      let(:locale) { "he" }
+
+      it "raises an error" do
+        expect(output).to match(/Failed to compile message formats/)
+      end
+    end
   end
 end