FIX: Abort CensoredWordsValidator early if censored_words_regexp nil (#8375)

* Abort CensoredWordsValidator early if censored_words_regexp nil. Sometimes censored_words_regex can end up nil, erroring the validator. This handles the nil condition and also adds a spec for the validator

spec/lib/validators/censored_words_validator_spec.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe CensoredWordsValidator do
+  let(:value) { 'some new bad text' }
+  let(:record) { Fabricate(:post, raw: 'this is a test') }
+  let(:attribute) { :raw }
+
+  describe "#validate_each" do
+    context "when there are censored words for action" do
+      let!(:watched_word) { Fabricate(:watched_word, action: WatchedWord.actions[:censor], word: 'bad') }
+
+      context "when there is a nil word_matcher_regexp" do
+        before do
+          WordWatcher.stubs(:word_matcher_regexp).returns(nil)
+        end
+
+        it "adds no errors to the record" do
+          validate
+          expect(record.errors.empty?).to eq(true)
+        end
+      end
+
+      context "when there is word_matcher_regexp" do
+        context "when the new value does not contain the watched word" do
+          let(:value) { 'some new good text' }
+
+          it "adds no errors to the record" do
+            validate
+            expect(record.errors.empty?).to eq(true)
+          end
+        end
+
+        context "when the new value does contain the watched word" do
+          let(:value) { 'some new bad text' }
+
+          it "adds errors to the record" do
+            validate
+            expect(record.errors.empty?).to eq(false)
+          end
+        end
+      end
+    end
+  end
+
+  def validate
+    described_class.new(attributes: :test).validate_each(record, attribute, value)
+  end
+end