Set asserts in kitchen_sink_proc_macro.rs

[makorne]

I tried the kitchen_sink_proc_macro example and found that custom cache has hits: None and misses: None

target/debug/kitchen_sink_proc_macro`

default cache with default name hits: Some(2) misses: Some(4)

default cache with explicit name hits: Some(1) misses: Some(1)

specific cache hits: Some(19) misses: Some(21)

custom cache hits: None misses: None

Looks like Custom cache does not work. I set asserts for this example please check it.