diff --git a/src/Controller/PluginRevisionController.php b/src/Controller/PluginRevisionController.php
index 6205ae1..32d14c4 100644
--- a/src/Controller/PluginRevisionController.php
+++ b/src/Controller/PluginRevisionController.php
@@ -250,7 +250,7 @@ class PluginRevisionController extends ControllerBase {
       ];
       $i = 0;
       // Find the previous revision.
-      while ($left_revision_id > $revision_ids[$i]) {
+      while (!empty($revision_ids[$i]) && $left_revision_id > $revision_ids[$i]) {
         $i += 1;
       }
       if ($i != 0) {
@@ -265,7 +265,7 @@ class PluginRevisionController extends ControllerBase {
       ];
       // Find the next revision.
       $i = 0;
-      while ($i < $revisions_count && $right_revision_id >= $revision_ids[$i]) {
+      while (!empty($revision_ids[$i]) && $right_revision_id >= $revision_ids[$i]) {
         $i += 1;
       }
       if ($revisions_count != $i && $revision_ids[$i - 1] != $revision_ids[$revisions_count - 1]) {