fix: Do not convert linebreaks in pre blocks on markdown parsing

lib/src/utils/markdown.dart

@@ -258,8 +258,21 @@ String markdown(
       // Remove trailing linebreaks
       .replaceAll(RegExp(r'(<br />)+$'), '');
   if (convertLinebreaks) {
-    ret = ret.replaceAll('\n', '<br/>');
+    // Only convert linebreaks which are not in <pre> blocks
+    ret = ret.convertLinebreaksToBr();
   }
 
   return ret;
 }
+
+extension on String {
+  String convertLinebreaksToBr() {
+    final parts = split('pre>');
+    var convertLinebreaks = true;
+    for (var i = 0; i < parts.length; i++) {
+      if (convertLinebreaks) parts[i] = parts[i].replaceAll('\n', '<br/>');
+      convertLinebreaks = !convertLinebreaks;
+    }
+    return parts.join('pre>');
+  }
+}

test/markdown_test.dart

@@ -123,5 +123,22 @@ void main() {
       expect(markdown('meep `\$\\frac{2}{3}\$`'),
           'meep <code>\$\\frac{2}{3}\$</code>');
     });
+    test('Code blocks', () {
+      expect(
+        markdown(
+          '```dart\nvoid main(){\nprint(something);\n}\n```',
+          convertLinebreaks: true,
+        ),
+        '<pre><code class="language-dart">void main(){\nprint(something);\n}\n</code></pre>',
+      );
+
+      expect(
+        markdown(
+          'The first \n codeblock\n```dart\nvoid main(){\nprint(something);\n}\n```\nAnd the second code block\n```js\nmeow\nmeow\n```',
+          convertLinebreaks: true,
+        ),
+        '<p>The first<br/>codeblock</p><br/><pre><code class="language-dart">void main(){\nprint(something);\n}\n</code></pre><br/><p>And the second code block</p><br/><pre><code class="language-js">meow\nmeow\n</code></pre>',
+      );
+    });
   });
 }