Fixes polkadart examples

[leonardocustodio]

User description

@justkawal I suggest doing this for now, seems to be the fastest way and that will not break everything you have done. Refactoring can be done later.

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PR Type

Enhancement, Tests

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Description

• Added new example scripts for demonstrating Polkadart functionalities.

• Introduced support for RuntimeMetadata in Registry class.

• Updated dependencies to include substrate_metadata.

• Added dependency overrides for substrate_metadata.

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Changes walkthrough 📝

	Relevant files
Tests	encointer_extrinsic_demo.dart Added Encointer extrinsic demo example                                      examples/lib/encointer_extrinsic_demo.dart Added a new example demonstrating ChargeAssetTxPayment signed extension. Showcased usage of custom signed extensions with TypeRegistry. Included detailed steps for setting up and running the example. +141/-0  extrinsic_demo.dart Added general extrinsic demo example                                          examples/lib/extrinsic_demo.dart Added a new example for creating and submitting extrinsics. Demonstrated wallet creation and fund transfer between wallets. Included custom RPC call and signed extension examples. +274/-0  get_account_infos_demo.dart Added account information retrieval demo                                  examples/lib/get_account_infos_demo.dart Added a new example for fetching account information. Demonstrated decoding of account storage keys and fetching AccountInfo. +33/-0
Enhancement	core.dart Added RuntimeMetadata support in core library                        packages/polkadart_scale_codec/lib/core/core.dart Imported RuntimeMetadata from substrate_metadata. Updated core library to support metadata-based registry initialization. +2/-0      registry.dart Enhanced Registry with RuntimeMetadata constructor              packages/polkadart_scale_codec/lib/core/registry.dart Added Registry.fromRuntimeMetadata constructor. Enabled initialization of registry using runtime metadata. +7/-0
Dependencies	pubspec.yaml Updated dependencies to include substrate_metadata              packages/polkadart_scale_codec/pubspec.yaml Added substrate_metadata as a dependency. +1/-0
Configuration changes	pubspec_overrides.yaml Added dependency override for substrate_metadata                  packages/polkadart_scale_codec/pubspec_overrides.yaml Added dependency override for substrate_metadata. +4/-0

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[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 4 🔵🔵🔵🔵⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Possible Issue The ChargeAssetTxPayment signed extension is being used with a custom asset_id. Ensure that the Option.some(paymentAsset.toJson()) implementation is correct and compatible with the expected runtime behavior. customSignedExtensions: <String, dynamic>{ 'ChargeAssetTxPayment': { "tip": BigInt.zero, "asset_id": Option.some(paymentAsset.toJson()), }, // A custom Signed Extensions }, Incomplete Implementation The Registry.fromRuntimeMetadata constructor currently has a placeholder implementation for processing runtimeMetadata.types. This needs to be reviewed and completed to avoid potential runtime issues. Registry.fromRuntimeMetadata(RuntimeMetadata runtimeMetadata) { runtimeMetadata.types.forEach((type) => { // This needs to be done, so we don't break the other packages for now // Remove the type and let it be dynamic so we don't need to depend on substrate_metadata if possible }); Potential Error Handling Gap The extrinsic submission process does not include error handling for potential failures during submitExtrinsic. Ensure that errors are caught and logged to prevent silent failures. final srHash = await author.submitExtrinsic(srExtrinsic); print('Sr25519 extrinsic hash: ${hex.encode(srHash)}');

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
General	Replace blocking sleep with async delay Ensure the sleep function does not block the main thread by using asynchronous alternatives like Future.delayed. examples/lib/extrinsic_demo.dart [116] -sleep(Duration(seconds: 10)); +await Future.delayed(Duration(seconds: 10)); Suggestion importance[1-10]: 9 Why: Replacing the blocking sleep function with an asynchronous alternative prevents the main thread from being blocked, improving the application's responsiveness and adhering to best practices in asynchronous programming.	9
	Add error handling for async calls Add error handling for the await calls to ensure the application can gracefully handle potential failures, such as network issues or invalid responses. examples/lib/encointer_extrinsic_demo.dart [57-60] -final encointerRuntimeVersion = await encointerState.getRuntimeVersion(); -final encointerSpecVersion = encointerRuntimeVersion.specVersion; -final encointerTransactionVersion = encointerRuntimeVersion.transactionVersion; +try { + final encointerRuntimeVersion = await encointerState.getRuntimeVersion(); + final encointerSpecVersion = encointerRuntimeVersion.specVersion; + final encointerTransactionVersion = encointerRuntimeVersion.transactionVersion; +} catch (e) { + print('Error fetching runtime version: $e'); + return; +} Suggestion importance[1-10]: 8 Why: Adding error handling for the async calls improves the robustness of the application by ensuring it can handle potential failures gracefully, such as network issues or invalid responses. This is a significant enhancement to the code's reliability.	8
	Validate response from getKeysPaged Validate the response from getKeysPaged to handle cases where the returned keys might be null or empty, avoiding potential runtime errors. examples/lib/get_account_infos_demo.dart [13-14] final keys = await polkadot.rpc.state.getKeysPaged(key: accountMapPrefix, count: 10); +if (keys == null || keys.isEmpty) { + print('No keys found.'); + return; +} Suggestion importance[1-10]: 7 Why: Validating the response from getKeysPaged ensures that the application can handle cases where the returned keys are null or empty, preventing potential runtime errors. This is a useful improvement for error handling.	7
Possible issue	Add null check for metadata types Add a safeguard to ensure runtimeMetadata.types is not null before iterating, preventing potential null pointer exceptions. packages/polkadart_scale_codec/lib/core/registry.dart [21-24] -runtimeMetadata.types.forEach((type) => { - // This needs to be done, so we don't break the other packages for now - // Remove the type and let it be dynamic so we don't need to depend on substrate_metadata if possible - }); +if (runtimeMetadata.types != null) { + runtimeMetadata.types.forEach((type) => { + // This needs to be done, so we don't break the other packages for now + // Remove the type and let it be dynamic so we don't need to depend on substrate_metadata if possible + }); +} else { + print('Runtime metadata types are null.'); +} Suggestion importance[1-10]: 8 Why: Adding a null check for runtimeMetadata.types prevents potential null pointer exceptions, enhancing the code's safety and reliability. This is a valuable safeguard for handling unexpected input.	8