WASM SDK: Inconsistent use of JsValue::UNDEFINED vs JsValue::NULL in proof responses

[thephez]

Description

Some *WithProof query methods use JsValue::UNDEFINED when there's no data to return, while others correctly use JsValue::NULL. When JsValue::UNDEFINED is used, the data property is omitted entirely from the JSON response (standard JS behavior - undefined values are not serialized).

Current behavior (inconsistent queries):

{
  "metadata": { ... },
  "proof": { ... }
}

Expected behavior (all queries should match this):

{
  "data": null,
  "metadata": { ... },
  "proof": { ... }
}

Affected Methods (using JsValue::UNDEFINED - incorrect)

File	Line	Method
address.rs	107	getPlatformAddressWithProof
address.rs	152, 202	getPlatformAddressesWithProof (per-address in map)
group.rs	945	getGroupMembersWithProof
token.rs	847	getTokenContractInfoWithProof
token.rs	893	getTokenPerpetualDistributionLastClaimWithProof
system.rs	967	getTotalCreditsInPlatformWithProof
system.rs	1004	getPrefundedSpecializedBalanceWithProof

Already Correct (using JsValue::NULL)

These methods already handle this correctly and can serve as reference:

• identity.rs:354 - getIdentityWithProof
• identity.rs:594 - getIdentityNonceWithProof
• identity.rs:667 - getIdentityContractNonceWithProof
• identity.rs:1041 - getIdentityBalanceWithProof
• identity.rs:1089 - getIdentitiesBalancesWithProof
• identity.rs:1126 - getIdentityBalanceAndRevisionWithProof
• identity.rs:1168 - getIdentityByPublicKeyHashWithProof
• document.rs:348, 383 - document queries
• token.rs:659 - getTokenTotalSupplyWithProof

Suggested Fix

Change .unwrap_or(JsValue::UNDEFINED) to .unwrap_or(JsValue::NULL) in the affected locations.

Example in system.rs:1004:

// Before
.unwrap_or(JsValue::UNDEFINED)

// After
.unwrap_or(JsValue::NULL)

Impact

Consumers of the SDK cannot reliably check for "no data" vs "malformed response" when the data property is missing entirely. This was discovered via evo-sdk-website e2e tests which validate that all proof responses have { data, metadata, proof } structure.

Related to #2986