Fix segfault in predexp tests on Node 11
Fix segfault in predexp tests on Node 11

When passing the result of a JS callback through the Command
Callback/ErrorCallback functions, ensure the value is escaped in every
scope.

aerospike/aerospike-client-nodejs,aerospike/aerospike-client-nodejs,aerospike/aerospike-client-nodejs,aerospike/aerospike-client-nodejs,aerospike/aerospike-client-nodejs