fix(ExtrinsicPayload): decode assetId with and without option (#6037)

Author: carlosala

packages/types/src/extrinsic/ExtrinsicPayload.spec.ts

@@ -55,6 +55,8 @@ describe('ExtrinsicPayload', (): void => {
 
     reg.setSignedExtensions(fallbackExtensions.concat(['ChargeAssetTxPayment']));
     const ext = new ExtrinsicPayload(reg, TEST_WITH_ASSET, { version: 4 });
+    // remove option byte
+    const ext2 = new ExtrinsicPayload(reg, { ...TEST_WITH_ASSET, assetId: `0x${TEST_WITH_ASSET.assetId.slice(4)}` }, { version: 4 });
 
     expect(ext.assetId.toJSON()).toEqual({
       interior: {
@@ -69,6 +71,7 @@ describe('ExtrinsicPayload', (): void => {
       },
       parents: 0
     });
+    expect(ext.assetId.toJSON()).toEqual(ext2.assetId.toJSON());
   });
 
   it('handles toU8a(true) correctly', (): void => {

packages/types/src/extrinsic/ExtrinsicPayload.ts

@@ -57,12 +57,18 @@ function decodeExtrinsicPayload (registry: Registry, value?: GenericExtrinsicPay
    * ref: https://github.com/polkadot-js/api/pull/5967
    */
   if (value && (value as ExtrinsicPayloadValue).assetId && isHex((value as ExtrinsicPayloadValue).assetId)) {
-    const adjustedPayload = {
-      ...(value as ExtrinsicPayloadValue),
-      assetId: registry.createType('TAssetConversion', hexToU8a((value as ExtrinsicPayloadValue).assetId)).toJSON()
-    };
-
-    return registry.createTypeUnsafe(extVersion, [adjustedPayload, { version }]);
+    const assetId = registry.createType('TAssetConversion', hexToU8a((value as ExtrinsicPayloadValue).assetId));
+
+    // we only want to adjust the payload if the hex passed has the option
+    if ((value as ExtrinsicPayloadValue).assetId === '0x00' ||
+      (value as ExtrinsicPayloadValue).assetId === '0x01' + assetId.toHex().slice(2)) {
+      const adjustedPayload = {
+        ...(value as ExtrinsicPayloadValue),
+        assetId: assetId.toJSON()
+      };
+
+      return registry.createTypeUnsafe(extVersion, [adjustedPayload, { version }]);
+    }
   }
 
   return registry.createTypeUnsafe(extVersion, [value, { version }]);