n-api: allow escape of undefined
The node-addon-api module was calling escape on undefined which would fail. Instead of forcing a check in all consumers of napi_escape_handle accept undefined and simply return it as it does not need to be escaped.
Refs: https://github.com/nodejs/node-addon-api/issues/233
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines