Remove exception because it breaks the upgrade.

app/Models/PiggyBank.php

@@ -87,7 +87,7 @@ class PiggyBank extends Model
 
     public function account(): BelongsTo
     {
-        throw new FireflyException('This method is not available on PiggyBank.');
+        return $this->belongsTo(Account::class);
     }
 
     public function attachments(): MorphMany

database/migrations/2024_11_30_075826_multi_piggy.php

@@ -23,7 +23,6 @@ return new class () extends Migration {
         });
         Schema::table('piggy_banks', static function (Blueprint $table): void {
             // 3. add currency
-
             $table->integer('transaction_currency_id', false, true)->after('account_id')->nullable();
             $table->foreign('transaction_currency_id', 'unique_currency')->references('id')->on('transaction_currencies')->onDelete('cascade');
         });