fix: unset hash128 fields using AccountSet (#2156)

packages/ripple-binary-codec/src/types/hash-128.ts

@@ -9,8 +9,25 @@ class Hash128 extends Hash {
   static readonly ZERO_128: Hash128 = new Hash128(Buffer.alloc(Hash128.width))
 
   constructor(bytes: Buffer) {
+    if (bytes && bytes.byteLength === 0) {
+      bytes = Hash128.ZERO_128.bytes
+    }
+
     super(bytes ?? Hash128.ZERO_128.bytes)
   }
+
+  /**
+   * Get the hex representation of a hash-128 bytes, allowing unset
+   *
+   * @returns hex String of this.bytes
+   */
+  toHex(): string {
+    const hex = this.toBytes().toString('hex').toUpperCase()
+    if (/^0+$/.exec(hex)) {
+      return ''
+    }
+    return hex
+  }
 }
 
 export { Hash128 }