Various PHP 8.1 strlen(null) fixes for Dashboard Panels

Summary:
In the dashboard application (https://my.phorge.site/dashboard/), when creating panels, adding panels to tab panels, and viewing query panels, we get a variety of strlen(null) errors under PHP 8.1.

This fixes all the ones seen.

Fixes T15574

Test Plan: See T15574

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

Subscribers: avivey, speck, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15574

Differential Revision: https://we.phorge.it/D25367

Author: campbsb

src/applications/dashboard/controller/dashboard/PhabricatorDashboardAdjustController.php

@@ -32,7 +32,7 @@ public function handleRequest(AphrontRequest $request) {
 
     $panel_ref = null;
     $panel_key = $request->getStr('panelKey');
-    if (strlen($panel_key)) {
+    if ($panel_key !== null && strlen($panel_key)) {
       $panel_ref = $ref_list->getPanelRef($panel_key);
       if (!$panel_ref) {
         return new Aphront404Response();

src/applications/dashboard/controller/panel/PhabricatorDashboardPanelTabsController.php

@@ -41,12 +41,12 @@ public function handleRequest(AphrontRequest $request) {
 
     $op = $request->getURIData('op');
     $after = $request->getStr('after');
-    if (!strlen($after)) {
+    if ($after === '') {
       $after = null;
     }
 
     $target = $request->getStr('target');
-    if (!strlen($target)) {
+    if ($target === '') {
       $target = null;
     }
 

src/applications/dashboard/engine/PhabricatorDashboardPanelRenderingEngine.php

@@ -155,6 +155,7 @@ public function renderPanel() {
 
       return $this->renderNormalPanel();
     } catch (Exception $ex) {
+      phlog($ex);
       return $this->renderErrorPanel(
         $panel->getName(),
         pht(

src/applications/dashboard/paneltype/PhabricatorDashboardTabsPanelType.php

@@ -100,7 +100,7 @@ public function renderPanelContent(
       $panel_id = idx($tab_spec, 'panelID');
       $subpanel = idx($panels, $panel_id);
 
-      $name = idx($tab_spec, 'name');
+      $name = coalesce(idx($tab_spec, 'name'), '');
       if (!strlen($name)) {
         if ($subpanel) {
           $name = $subpanel->getName();

src/applications/search/engineextension/PhabricatorFerretSearchEngineExtension.php

@@ -27,7 +27,7 @@ public function applyConstraintsToQuery(
     PhabricatorSavedQuery $saved,
     array $map) {
 
-    if (!strlen($map['query'])) {
+    if (!(isset($map['query']) && strlen($map['query']))) {
       return;
     }