Fix phpstan issues.

app/Factory/BudgetFactory.php

@@ -50,7 +50,7 @@ class BudgetFactory
 
         // first by ID:
         if ($budgetId > 0) {
-            /** @var Budget $budget */
+            /** @var Budget|null $budget */
             $budget = $this->user->budgets()->find($budgetId);
             if (null !== $budget) {
                 return $budget;

app/Factory/CategoryFactory.php

@@ -54,7 +54,7 @@ class CategoryFactory
         }
         // first by ID:
         if ($categoryId > 0) {
-            /** @var Category $category */
+            /** @var Category|null $category */
             $category = $this->user->categories()->find($categoryId);
             if (null !== $category) {
                 return $category;

app/Factory/PiggyBankFactory.php

@@ -48,7 +48,7 @@ class PiggyBankFactory
         }
         // first find by ID:
         if ($piggyBankId > 0) {
-            /** @var PiggyBank $piggyBank */
+            /** @var PiggyBank|null $piggyBank */
             $piggyBank = $this->user->piggyBanks()->find($piggyBankId);
             if (null !== $piggyBank) {
                 return $piggyBank;
@@ -57,7 +57,7 @@ class PiggyBankFactory
 
         // then find by name:
         if ('' !== $piggyBankName) {
-            /** @var PiggyBank $piggyBank */
+            /** @var PiggyBank|null $piggyBank */
             $piggyBank = $this->findByName($piggyBankName);
             if (null !== $piggyBank) {
                 return $piggyBank;

app/Factory/TagFactory.php

@@ -92,6 +92,7 @@ class TagFactory
             'longitude'     => null,
             'zoomLevel'     => null,
         ];
+        /** @var Tag|null $tag */
         $tag       = Tag::create($array);
         if (null !== $tag && null !== $latitude && null !== $longitude) {
             // create location object.

app/Factory/TransactionFactory.php

@@ -127,7 +127,9 @@ class TransactionFactory
         );
 
         // do foreign currency thing: add foreign currency info to $one and $two if necessary.
-        if (null !== $this->foreignCurrency && null !== $foreignAmount && $this->foreignCurrency->id !== $this->currency->id && '' !== $foreignAmount) {
+        if (null !== $this->foreignCurrency &&
+            null !== $foreignAmount &&
+            $this->foreignCurrency->id !== $this->currency->id) {
             $result->foreign_currency_id = $this->foreignCurrency->id;
             $result->foreign_amount      = $foreignAmount;
         }