observeQuery errors without including selectionSet

### Before opening, please confirm:


- [x] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-js/issues?q=is%3Aissue+) and [discussions](https://github.com/aws-amplify/amplify-js/discussions).
- [x] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-js/blob/main/CONTRIBUTING.md#bug-reports).
- [x] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

### JavaScript Framework

React

### Amplify APIs

GraphQL API

### Amplify Version

v6

### Amplify Categories

api

### Backend

Amplify Gen 2

### Environment information

<details>

```
# Put output below this line
System:
    OS: macOS 15.5
    CPU: (8) arm64 Apple M1 Pro
    Memory: 106.42 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.12.0 - ~/.nvm/versions/node/v22.12.0/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 11.6.1 - ~/.nvm/versions/node/v22.12.0/bin/npm
    Watchman: 2025.05.26.00 - /opt/homebrew/bin/watchman
  Browsers:
    Brave Browser: 123.1.64.116
    Chrome: 140.0.7339.215
    Edge: 140.0.3485.94
    Safari: 18.5
  npmPackages:
    @aws-amplify/backend: ^1.16.1 => 1.16.1 
    @aws-amplify/backend-cli: ^1.8.0 => 1.8.0 
    @aws-amplify/ui-react: ^6.12.0 => 6.12.0 
    @aws-amplify/ui-react-internal:  undefined ()
    @aws-amplify/ui-react-server:  undefined ()
    @aws-sdk/client-eventbridge: ^3.891.0 => 3.891.0 
    @aws-sdk/lib-dynamodb: ^3.888.0 => 3.890.0 
    @aws-sdk/util-dynamodb: ^3.888.0 => 3.890.0 
    @dotenvx/dotenvx: ^1.49.1 => 1.49.1 
    @headlessui/react: ^2.2.8 => 2.2.8 
    @heroicons/react: ^2.2.0 => 2.2.0 
    @reduxjs/toolkit: ^2.9.0 => 2.9.0 
    @reduxjs/toolkit-query:  1.0.0 
    @reduxjs/toolkit-query-react:  1.0.0 
    @reduxjs/toolkit-react:  1.0.0 
    @tailwindcss/forms: ^0.5.10 => 0.5.10 
    @tailwindcss/postcss: ^4.1.13 => 4.1.13 
    @tailwindcss/vite: ^4.1.13 => 4.1.13 
    @testing-library/jest-dom: ^6.8.0 => 6.8.0 
    @testing-library/react: ^16.3.0 => 16.3.0 
    @types/aws-lambda: ^8.10.152 => 8.10.152 
    @types/crypto-js: ^4.2.2 => 4.2.2 
    @types/react: ^19.1.10 => 19.1.13 
    @types/react-dom: ^19.1.7 => 19.1.9 
    @types/react-modal: ^3.16.3 => 3.16.3 
    @types/redux-mock-store: ^1.5.0 => 1.5.0 
    @types/testing-library__jest-dom: ^5.14.9 => 5.14.9 
    @types/testing-library__react: ^10.0.1 => 10.0.1 
    @typescript-eslint/eslint-plugin: ^6.2.1 => 6.21.0 
    @typescript-eslint/parser: ^6.2.1 => 6.21.0 
    @vis.gl/react-google-maps: ^1.5.5 => 1.5.5 
    @vitejs/plugin-react: ^5.0.2 => 5.0.3 
    @vitejs/plugin-react-swc: ^4.0.0 => 4.1.0 
    autoprefixer: ^10.4.21 => 10.4.21 
    aws-amplify: ^6.15.6 => 6.15.6 
    aws-amplify/adapter-core:  undefined ()
    aws-amplify/adapter-core/internals:  undefined ()
    aws-amplify/analytics:  undefined ()
    aws-amplify/analytics/kinesis:  undefined ()
    aws-amplify/analytics/kinesis-firehose:  undefined ()
    aws-amplify/analytics/personalize:  undefined ()
    aws-amplify/analytics/pinpoint:  undefined ()
    aws-amplify/api:  undefined ()
    aws-amplify/api/internals:  undefined ()
    aws-amplify/api/server:  undefined ()
    aws-amplify/auth:  undefined ()
    aws-amplify/auth/cognito:  undefined ()
    aws-amplify/auth/cognito/server:  undefined ()
    aws-amplify/auth/enable-oauth-listener:  undefined ()
    aws-amplify/auth/server:  undefined ()
    aws-amplify/data:  undefined ()
    aws-amplify/data/server:  undefined ()
    aws-amplify/datastore:  undefined ()
    aws-amplify/in-app-messaging:  undefined ()
    aws-amplify/in-app-messaging/pinpoint:  undefined ()
    aws-amplify/push-notifications:  undefined ()
    aws-amplify/push-notifications/pinpoint:  undefined ()
    aws-amplify/storage:  undefined ()
    aws-amplify/storage/s3:  undefined ()
    aws-amplify/storage/s3/server:  undefined ()
    aws-amplify/storage/server:  undefined ()
    aws-amplify/utils:  undefined ()
    aws-cdk-lib: ^2.215.0 => 2.215.0 
    constructs: ^10.4.2 => 10.4.2 
    crypto-js: ^4.2.0 => 4.2.0 
    date-fns: ^4.1.0 => 4.1.0 
    esbuild: ^0.25.9 => 0.25.10 
    eslint: ^8.46.0 => 8.57.1 
    eslint-config-prettier: ^8.10.0 => 8.10.2 
    eslint-plugin-prettier: ^5.0.0 => 5.5.4 
    eslint-plugin-react: ^7.33.1 => 7.37.5 
    eslint-plugin-react-hooks: ^4.6.0 => 4.6.2 
    eslint-plugin-tailwindcss: ^3.13.0 => 3.18.2 
    form-data: ^4.0.4 => 4.0.4 
    glob: ^11.0.3 => 11.0.3 (7.2.3, 10.4.5)
    globals: ^16.3.0 => 16.4.0 (13.24.0)
    heroicons: ^2.2.0 => 2.2.0 
    postcss: ^8.5.6 => 8.5.6 
    prettier: ^3.6.2 => 3.6.2 (2.3.2, 1.19.1)
    react: ^19.1.1 => 19.1.1 (18.3.1)
    react-datepicker: ^8.7.0 => 8.7.0 
    react-dom: ^19.1.1 => 19.1.1 (18.3.1)
    react-modal: ^3.16.3 => 3.16.3 
    react-number-format: ^5.4.4 => 5.4.4 
    react-redux: ^9.2.0 => 9.2.0 
    react-router-dom: ^7.9.1 => 7.9.1 
    react-tooltip: ^5.29.1 => 5.29.1 
    rimraf: ^6.0.1 => 6.0.1 (3.0.2)
    tailwindcss: ^3.4.17 => 3.4.17 (4.1.13)
    ts-jest: ^29.4.1 => 29.4.2 
    tsx: ^4.20.5 => 4.20.5 (4.19.4)
    typescript: ^5.9.2 => 5.9.2 (4.4.4, 4.9.5)
    vite: ^7.1.2 => 7.1.5 
    vitest: ^3.2.4 => 3.2.4 
  npmGlobalPackages:
    corepack: 0.29.4
    npm: 11.6.1

```

</details>


### Describe the bug

I'm following this [observeQuery example in the gen2 docs](https://docs.amplify.aws/javascript/build-a-backend/data/subscribe-data/) and kept getting this error: 

`Uncaught TypeError: needle is null` from amplify internal file findIndexByFields.ts

I resolved this by including selectionSet param, listing the properties requested. 



### Expected behavior

I was unaware of this selectionSet param because it wasn't in the docs page, and just assumed all properties would be returned.

### Reproduction steps

1. Create subscription observeQuery without the selectionSet specified, 
2. do some graphql create or update on the observed table

<img width="1310" height="430" alt="Image" src="https://github.com/user-attachments/assets/353cd05c-c064-4c41-a369-9d5960a5f705" />

### Code Snippet

```javascript
// Put your code below this line.
// working example with selectionSet
const querySub = client.models.VendorResult.observeQuery({
      filter: { searchSessionID: { eq: searchSessionID } },
      selectionSet: ["id", "status", "createdAt"],
      authMode: "userPool",
    }).subscribe({
      next: ({ items, isSynced }) => {
        console.log("Subscription received items:", items, "isSynced:", isSynced);
        
      },
      error: (err) => console.error("subscription error", err),
    });
```


### Log output

<details>

```
// Put your logs below this line

Subscription received items: 
Array []
 isSynced: false [SubscribedVendorList.tsx:57:17](http://localhost:5173/src/components/VendorIndex/FindVendors/SubscribedVendorList.tsx)
Subscription received items: 
Array []
 isSynced: true [SubscribedVendorList.tsx:57:17](http://localhost:5173/src/components/VendorIndex/FindVendors/SubscribedVendorList.tsx)
Uncaught TypeError: can't access property "id", needle is null
    searchObject findIndexByFields.ts:12
    findIndexByFields findIndexByFields.ts:12
    ingestMessages observeQuery.ts:47
    receiveMessages observeQuery.ts:100
    next observeQuery.ts:22
    RxJS 8
    _handleSubscriptionData index.ts:67
    _handleIncomingSubscriptionMessage index.ts:427
    _registerWebsocketHandlers index.ts:676
    onmessage index.ts:641
    _initiateHandshake index.ts:631
    _initiateHandshake index.ts:617
    _establishConnection index.ts:35
    retry retry.ts:39
    retry retry.ts:16
    jitteredExponentialRetry jitteredExponentialRetry.ts:10
    _establishRetryableConnection index.ts:592
    _initializeWebSocketConnection index.ts:566
    _initializeWebSocketConnection index.ts:541
    _connectWebSocket index.ts:149
    _startSubscriptionWithAWSAppSyncRealTime index.ts:281
    startSubscription index.ts:106
    subscribe index.ts:127
    RxJS 14
    observeQuery observeQuery.ts:20
    RxJS 4
    SubscribedVendorList SubscribedVendorList.tsx:55
    React 8
```

</details>


### aws-exports.js

_No response_

### Manual configuration

_No response_

### Additional configuration

_No response_

### Mobile Device

_No response_

### Mobile Operating System

_No response_

### Mobile Browser

_No response_

### Mobile Browser Version

_No response_

### Additional information and screenshots

_No response_

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observeQuery errors without including selectionSet #14582

Before opening, please confirm:

JavaScript Framework

Amplify APIs

Amplify Version

Amplify Categories

Backend

Environment information

Describe the bug

Expected behavior

Reproduction steps

Code Snippet

Log output

aws-exports.js

Manual configuration

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Mobile Device

Mobile Operating System

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observeQuery errors without including selectionSet #14582

Description

Before opening, please confirm:

JavaScript Framework

Amplify APIs

Amplify Version

Amplify Categories

Backend

Environment information

Describe the bug

Expected behavior

Reproduction steps

Code Snippet

Log output

aws-exports.js

Manual configuration

Additional configuration

Mobile Device

Mobile Operating System

Mobile Browser

Mobile Browser Version

Additional information and screenshots

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions