Fix PHP notice when viewing issue without category

Regression from f1cf144.

We use the Command's flag to determine whether the label must be
displayed, and additionally that the category is indeed present in the
Issue's data before trying to access it.

Fixes #26094

bug_view_inc.php

@@ -218,12 +218,14 @@
 echo '<tbody>';
 
 if( $t_flags['id_show'] || $t_flags['project_show'] || $t_flags['category_show'] ||
-    isset( $t_issue['view_state'] ) || isset( $t_issue_view['created_at'] ) || isset( $t_issue_view['updated_at'] ) ) {
+    isset( $t_issue['view_state'] ) || isset( $t_issue_view['created_at'] ) || isset( $t_issue_view['updated_at'] )
+) {
+
 	# Labels
 	echo '<tr class="bug-header">';
 	echo '<th class="bug-id category" width="15%">', isset( $t_issue['id'] ) ? lang_get( 'id' ) : '', '</th>';
 	echo '<th class="bug-project category" width="20%">', isset( $t_issue['project'] ) && isset( $t_issue['project']['name'] ) ? lang_get( 'email_project' ) : '', '</th>';
-	echo '<th class="bug-category category" width="15%">', isset( $t_issue['category'] ) && isset( $t_issue['category']['name'] ) ? lang_get( 'category' ) : '', '</th>';
+	echo '<th class="bug-category category" width="15%">', $t_flags['category_show'] ? lang_get( 'category' ) : '', '</th>';
 	echo '<th class="bug-view-status category" width="15%">', isset( $t_issue['view_state'] ) ? lang_get( 'view_status' ) : '', '</th>';
 	echo '<th class="bug-date-submitted category" width="15%">', isset( $t_issue_view['created_at'] ) ? lang_get( 'date_submitted' ) : '', '</th>';
 	echo '<th class="bug-last-modified category" width="20%">', isset( $t_issue_view['updated_at'] ) ? lang_get( 'last_update' ) : '','</th>';
@@ -238,7 +240,11 @@
 	echo '<td class="bug-project">', $t_flags['project_show'] && isset( $t_issue['project']['name'] ) ? string_display_line( $t_issue['project']['name'] ) : '', '</td>';
 
 	# Category
-	echo '<td class="bug-category">', $t_flags['category_show'] ? string_display_line( $t_issue['category']['name'] ) : '', '</td>';
+	echo '<td class="bug-category">',
+		$t_flags['category_show'] && isset( $t_issue['category']['name'] )
+			? string_display_line( $t_issue['category']['name'] )
+			: '',
+		'</td>';
 
 	# View Status
 	echo '<td class="bug-view-status">', $t_flags['view_state_show'] && isset( $t_issue['view_state']['label'] ) ? string_display_line( $t_issue['view_state']['label'] ) : '', '</td>';