fix(sasl): add nilguard around token to prevent panic (#3076) #184

Job	Run time
Test with Kafka 2.0.1 / Test with Kafka 2.0.1	56s
Test with Kafka 2.0.1 / Test with Kafka 2.0.1	6m 27s
Test with Kafka 1.0.2 / Test with Kafka 1.0.2	6m 3s
Test with Kafka 1.0.2 / Test with Kafka 1.0.2	6m 3s
Test with Kafka 2.2.2 / Test with Kafka 2.2.2	6m 59s
Test with Kafka 2.2.2 / Test with Kafka 2.2.2	6m 59s
Test with Kafka 2.6.3 / Test with Kafka 2.6.3	6m 51s
Test with Kafka 2.6.3 / Test with Kafka 2.6.3	6m 51s
Test with Kafka 2.8.2 / Test with Kafka 2.8.2	6m 53s
Test with Kafka 2.8.2 / Test with Kafka 2.8.2	6m 53s
Test with Kafka 3.0.2 / Test with Kafka 3.0.2	7m 22s
Test with Kafka 3.0.2 / Test with Kafka 3.0.2	7m 2s
Test with Kafka 3.3.2 / Test with Kafka 3.3.2	6m 52s
Test with Kafka 3.3.2 / Test with Kafka 3.3.2	6m 52s
Test with Kafka 3.6.2 / Test with Kafka 3.6.2	6m 34s
Test with Kafka 3.6.2 / Test with Kafka 3.6.2	6m 34s
Test with Kafka 3.8.1 / Test with Kafka 3.8.1	7m 8s
Test with Kafka 3.8.1 / Test with Kafka 3.8.1	7m 8s
Test with Kafka 4.0.0 / Test with Kafka 4.0.0	10m 53s
Test with Kafka 4.0.0 / Test with Kafka 4.0.0	10m 53s
	2h 18m 13s

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