fix: add transaction error reason transformer (#186)

# What ❔

Add transaction error reason transformer.

## Why ❔

To unsure error and reason are transformed correctly.

## Checklist

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packages/worker/src/entities/transaction.entity.ts

@@ -4,6 +4,7 @@ import { hexTransformer } from "../transformers/hex.transformer";
 import { Batch } from "./batch.entity";
 import { Block } from "./block.entity";
 import { CountableEntity } from "./countable.entity";
+import { stringTransformer } from "../transformers/string.transformer";
 
 @Entity({ name: "transactions" })
 @Index(["receivedAt", "transactionIndex"])
@@ -89,9 +90,9 @@ export class Transaction extends CountableEntity {
   @Column({ type: "int", default: 1 })
   public readonly receiptStatus: number;
 
-  @Column({ nullable: true })
+  @Column({ nullable: true, transformer: stringTransformer })
   public readonly error?: string;
 
-  @Column({ nullable: true })
+  @Column({ nullable: true, transformer: stringTransformer })
   public readonly revertReason?: string;
 }