test that nonexistant text will throw error

app/Plan/UseCases/CreatePlan.php

@@ -49,6 +49,9 @@ class CreatePlan
         }
         $textId = $request->textId;
         $text = $this->textRepo->find($textId);
+        if ($text === null) {
+            throw new DomainException("Text with id: $textId doesnt exist");
+        }
         $nodesOfText = $this->filterForNonParentNodes(
             $this->nodeRepo->findByTextId($textId)
         );

tests/Unit/Plan/UseCases/CreatePlanTest.php

@@ -43,6 +43,7 @@ class CreatePlanTest extends TestCase
             scheduledNodeRepo: $this->scheduledNodeRepo,
             planRepo: $this->planRepo,
         );
+        $this->textRepo->create(new CreateTextDto('testname'));
         $this->useCase = new CreatePlan(
             $this->planRepo,
             $this->userRepo,
@@ -83,11 +84,20 @@ class CreatePlanTest extends TestCase
         ));
     }
 
+    public function test_nonexistant_text_id_throws(): void
+    {
+        $this->expectException(DomainException::class);
+        $this->expectExceptionMessage("Text with id: 1 doesnt exist");
+        $plan = $this->useCase->execute(new CreatePlanRequest(
+            userId: 0,
+            name: 'testPlan',
+            textId: 1,
+        ));
+    }
+
     public function test_plan_schedules_nodes_on_creation(): void
     {
-        $text = $this->textRepo->create(new CreateTextDto(
+        $text = $this->textRepo->find(0);
-            name: 'testname',
-        ));
         $this->nodeRepo->create(new CreateNodeDto(
             text: $text,
             title: 'testtitle',
@@ -103,9 +113,7 @@ class CreatePlanTest extends TestCase
 
     public function test_plan_only_schedules_nodes_which_arent_parents(): void
     {
-        $text = $this->textRepo->create(new CreateTextDto(
+        $text = $this->textRepo->find(0);
-            name: 'testname',
-        ));
         $rootNode = $this->nodeRepo->create(new CreateNodeDto(
             text: $text,
             title: 'root node',