Event: Simplify the check for saved data in leverageNative

Event: Simplify the check for saved data in leverageNative

Previously, when `leverageNative` handled async events, there was
a case where an empty placeholder object was set as a result.
Covering both such an object and `false` required a `length` check.
However, this is not necessary since gh-5223 and the check was
already simplified in other places; this one was missed.

Closes gh-5236
Ref gh-5223

(cherry picked from commit dfe212d5a1eed6b4a67d1cbd04ece09bbac33699)