Fix two missed null value checks on the wiki page. (go-gitea#34205)

before:

![image](https://github.com/user-attachments/assets/83e5513f-a4fa-406d-a010-8ec8cd873203)

after:

![image](https://github.com/user-attachments/assets/6bca76c7-0445-429a-92b1-1a9f96d6daca)

(cherry picked from commit 3a651cf)

Author: kerwin612

templates/repo/wiki/revision.tmpl

@@ -6,7 +6,7 @@
 		<div class="ui stackable grid">
 			<div class="ui eight wide column">
 				<div class="ui header">
-					<a class="file-revisions-btn ui basic button" title="{{ctx.Locale.Tr "repo.wiki.back_to_wiki"}}" href="{{.RepoLink}}/wiki/{{.PageURL}}"><span>{{.revision}}</span> {{svg "octicon-home"}}</a>
+					<a class="file-revisions-btn ui basic button" title="{{ctx.Locale.Tr "repo.wiki.back_to_wiki"}}" href="{{.RepoLink}}/wiki/{{.PageURL}}">{{if .revision}}<span>{{.revision}}</span> {{end}}{{svg "octicon-home"}}</a>
 					{{$title}}
 					<div class="ui sub header tw-break-anywhere">
 						{{$timeSince := DateUtils.TimeSince .Author.When}}

templates/repo/wiki/view.tmpl

@@ -45,7 +45,7 @@
 		<div class="ui dividing header">
 			<div class="ui stackable grid">
 				<div class="eight wide column">
-					<a class="file-revisions-btn ui basic button" title="{{ctx.Locale.Tr "repo.wiki.file_revision"}}" href="{{.RepoLink}}/wiki/{{.PageURL}}?action=_revision" ><span>{{.CommitCount}}</span> {{svg "octicon-history"}}</a>
+					<a class="file-revisions-btn ui basic button" title="{{ctx.Locale.Tr "repo.wiki.file_revision"}}" href="{{.RepoLink}}/wiki/{{.PageURL}}?action=_revision" >{{if .CommitCount}}<span>{{.CommitCount}}</span> {{end}}{{svg "octicon-history"}}</a>
 					{{$title}}
 					<div class="ui sub header">
 						{{$timeSince := DateUtils.TimeSince .Author.When}}