Fix various problems (#37077)

Quick fix for 1.26.

* Slightly refactor NewComment to fix incorrect responses, remove
incorrect defer (still far from ideal)
* Avoid `const` causes js error in global scope
* Don't process markup contents on user's home activity feed, to avoid
js error due to broken math/mermaid code

* Fix #36582

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>

templates/repo/issue/view_content/pull_merge_box.tmpl

@@ -221,6 +221,7 @@
 						{{end}}
 						<div class="divider"></div>
 						<script type="module">
+						(() => {
 							const defaultMergeTitle = {{.DefaultMergeMessage}};
 							const defaultSquashMergeTitle = {{.DefaultSquashMergeMessage}};
 							const defaultMergeMessage = {{.DefaultMergeBody}};
@@ -299,6 +300,7 @@
 								}
 							];
 							window.config.pageData.pullRequestMergeForm = mergeForm;
+						})();
 						</script>
 
 						{{$showGeneralMergeForm = true}}