TypeError: FormsSteps::getFirstStep(): Return value must be of type Drupal\forms_steps\StepInterface

I hit the same issue. The issue occurs because:

1. FormsStepsListBuilder::getDefaultOperations() calls getFirstStep() to determine if a "View" operation should be shown
2. FormsSteps::getFirstStep() uses reset($steps) which returns FALSE when the array is empty
3. The method signature requires a StepInterface return type, but FALSE is returned instead

The fix involves:
1. Modifying getFirstStep() and getLastStep() to throw a descriptive exception when no steps exist
2. Updating FormsStepsListBuilder to catch this exception gracefully.

diff --git a/src/Builder/FormsStepsListBuilder.php b/src/Builder/FormsStepsListBuilder.php
index c932430..5c16ea9 100644
--- a/src/Builder/FormsStepsListBuilder.php
+++ b/src/Builder/FormsStepsListBuilder.php
@@ -47,18 +47,23 @@ class FormsStepsListBuilder extends ConfigEntityListBuilder {
   public function getDefaultOperations(EntityInterface $entity): array {
     /** @var \Drupal\Core\Config\Entity\ConfigEntityInterface $entity */
     $operations = parent::getDefaultOperations($entity);
-    $first_step = $entity->getFirstStep();
+    
+    try {
+      $first_step = $entity->getFirstStep();
+      // View action is only displayed when the forms steps has at least one step.
+      if ($first_step) {
+        $uri = $first_step->url();
 
-    // View action is only displayed when the forms steps has at least one step.
-    if ($first_step) {
-      $uri = $first_step->url();
-
-      $operations['display'] = [
-        'title' => $this->t('View'),
-        'weight' => 20,
-        'url' => Url::fromUri("internal:$uri"),
-      ];
+        $operations['display'] = [
+          'title' => $this->t('View'),
+          'weight' => 20,
+          'url' => Url::fromUri("internal:$uri"),
+        ];
+      }
+    } catch (\InvalidArgumentException $e) {
+      // No steps available, so no View operation will be shown.
     }
+    
     return $operations;
   }
 
diff --git a/src/Entity/FormsSteps.php b/src/Entity/FormsSteps.php
index 4ca1eb2..4b62d96 100644
--- a/src/Entity/FormsSteps.php
+++ b/src/Entity/FormsSteps.php
@@ -406,7 +406,11 @@ class FormsSteps extends ConfigEntityBase implements FormsStepsInterface {
     if ($steps === NULL) {
       $steps = $this->getSteps();
     }
-    return reset($steps);
+    $first_step = reset($steps);
+    if ($first_step === FALSE) {
+      throw new \InvalidArgumentException('No steps available to get first step.');
+    }
+    return $first_step;
 
   }
 
@@ -417,7 +421,11 @@ class FormsSteps extends ConfigEntityBase implements FormsStepsInterface {
     if ($steps === NULL) {
       $steps = $this->getSteps();
     }
-    return end($steps);
+    $last_step = end($steps);
+    if ($last_step === FALSE) {
+      throw new \InvalidArgumentException('No steps available to get last step.');
+    }
+    return $last_step;
 
   }
 

Attaching fix that addresses the InvalidArgumentException issue by:
- Adding proper exception handling in getFirstStep() and getLastStep() methods when no steps are available
- Catching the exception in the list builder to prevent crashes when displaying the operations