fix: guard against undefined/NaN port in reserveLoopbackPort close callback

The close callback used `=== null || <= 0` which fails to catch
undefined and NaN (both skip the guard in JS). Switch to `== null ||
!(port > 0)` so the check mirrors the error handler's positive-check
pattern and rejects any non-positive value.

Author: cursoragent

packages/shared/src/Net.ts

@@ -247,7 +247,10 @@ export const make = (
           addressDetails = resolvedAddressDetails;
 
           probe.close((cause) => {
-            if (resolvedAddressDetails.port === null || resolvedAddressDetails.port <= 0) {
+            if (
+              resolvedAddressDetails.port == null ||
+              !(resolvedAddressDetails.port > 0)
+            ) {
               settle(
                 Effect.fail(
                   new LoopbackPortAddressUnavailableError({