fix: testapp eth_signTypedData_v4 Example Message verify crash

[fan-zhang-sv]

Summary

Fixes the "Example Message" shortcut button for eth_signTypedData_v4 in the testapp playground, which was crashing with:

{ "message": "Cannot read properties of undefined (reading 'domain')" }

Cause

Introduced in #217 (commit 69fbee3b — "Fix SDK source reload and remove noExplicitAny suppressions"), a type-narrowing guard was added to the verify flow in RpcMethodCard.tsx:

// Before #217
message: data.message,

// After #217
message: typeof data.message === 'string' ? data.message : undefined,

This guard was intended to satisfy Biome's noExplicitAny rule, but it's overly restrictive. When shortcuts call submit(shortcut.data) directly (bypassing the form), data.message is a JavaScript object — not a JSON string — because the shortcut data stores typed data payloads as objects (required for replaceAddressInValue to do deep placeholder replacement like YOUR_ADDRESS_HERE). The guard drops the object and passes undefined to verifySignMsg, which then crashes on typedData['domain'].

The form-based path is unaffected because textarea values are always strings.

Fix

Pass data.message through as-is. verifySignMsg already handles both strings and objects correctly:

const typedData = typeof message === 'string' ? JSON.parse(message) : message;

This also affects eth_signTypedData_v3 shortcuts which have the same object-based message structure.

Test plan

• Open testapp playground
• Connect a wallet
• Under eth_signTypedData_v4, click the "Example Message" shortcut button
• Verify signature is submitted and verified without error
• Also test "Grant Permission" shortcut under eth_signTypedData_v4
• Also test "Example Message" shortcut under eth_signTypedData_v3

Made with Cursor

[cb-heimdall]

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