Fix various phpstan issues.

app/Http/Controllers/ProfileController.php

@@ -412,7 +412,7 @@ class ProfileController extends Controller
         // found user.which email address to return to?
         $set   = app('preferences')->beginsWith($user, 'previous_email_');
 
-        /** @var string $match */
+        /** @var string|null $match */
         $match = null;
         foreach ($set as $entry) {
             $hashed = hash('sha256', sprintf('%s%s', (string) config('app.key'), $entry->data));

app/Http/Controllers/Transaction/BulkController.php

@@ -117,7 +117,7 @@ class BulkController extends Controller
 
         // run rules on changed journals:
         /** @var TransactionJournal $journal */
-        foreach ($collection as $journal) {
+        foreach ($collection as $journal) { // @phpstan-ignore-line
             event(new UpdatedTransactionGroup($journal->transactionGroup, true, true, false));
         }
 

app/Http/Requests/RecurrenceFormRequest.php

@@ -138,7 +138,7 @@ class RecurrenceFormRequest extends FormRequest
          * @var int   $index
          * @var array $transaction
          */
-        foreach ($return['transactions'] as $index => $transaction) {
+        foreach ($return['transactions'] as $index => $transaction) { // @phpstan-ignore-line
             $categoryName = $transaction['category_name'] ?? null;
             if (null !== $categoryName) {
                 $category = $factory->findOrCreate(null, $categoryName);