SDK drift: `amount <= 0` guard in `getExecutionPriceDetailed`/`get_execution_price_detailed` diverges in error type and propagates asymmetric behavior into the non-detailed sibling method

[realfishsam]

Drift

Both getExecutionPriceDetailed (TS) and get_execution_price_detailed (Python) were rewritten in the same PR (#1308) to compute locally, adding a new defensive check for non-positive amount — but using different, non-equivalent exception types. Because Python's non-detailed get_execution_price delegates to get_execution_price_detailed, it inherits this validation and now raises for amount <= 0. TypeScript's non-detailed getExecutionPrice is an independent implementation with no such guard, so it silently returns a nonsensical numeric result instead of erroring.

TypeScript SDK

sdks/typescript/pmxt/client.ts:2808-2809 (in getExecutionPriceDetailed):

if (amount <= 0) {
    throw new Error('Amount must be greater than 0');
}

getExecutionPrice (sdks/typescript/pmxt/client.ts:2781-2793) has no equivalent guard — verified empirically: getExecutionPrice(orderBook, 'buy', 0) returns NaN, and getExecutionPrice(orderBook, 'buy', -5) returns a bogus price (e.g. 0.5) computed from the first book level, with no exception thrown.

Python SDK

sdks/python/pmxt/client.py:3429-3430 (in get_execution_price_detailed):

if amount <= 0:
    raise ValueError("Amount must be greater than 0")

get_execution_price (sdks/python/pmxt/client.py:3392-3410) delegates to get_execution_price_detailed, so it inherits this ValueError for the same inputs.

Expected

Both SDKs' non-detailed getExecutionPrice/get_execution_price methods should behave identically for amount <= 0 — either both should raise (with the same exception type, ideally a typed PmxtError/InvalidOrder rather than a bare Error/ValueError), or both should return a defined sentinel value without throwing.

Impact

Identical calls with identical (invalid) inputs produce a raised exception in Python and a silently wrong numeric result (NaN or a bogus price) in TypeScript — a real, user-facing functional difference that could let a caller compute and act on a nonsensical execution price in TypeScript without any error signal. This is not covered by existing issue #930 (scoped to create_order/build_order) or #931 (about getExecutionPriceDetailed's auth headers, now moot since the method no longer calls the server).

---

Found by automated SDK cross-language drift audit