A key not found in infinispan cache resulting in NullPointerException, sometime

Question

I would like to understand in which scenario when a key not found in cache it throws NullPointerException and in which scenario it just silently return null. We observed sometime no issue when keys are not there, but sometime it just ends up in exception. Why there are two different outcome? Not having a key in cache, is very common and it is just counted towards cache-miss. A cache name 'user-mapping-cahce' is

      <invalidation-cache name="user-mapping-cache" mode="ASYNC" statistics="true" configuration="invalidation-template">
        <persistence passivation="false">
            <remote:remote-store cache="user-mapping-cache" preload="false" shared="true" raw-values="false">
               <remote:connection-pool max-active="-1" min-idle="1" exhausted-action="WAIT" min-evictable-idle-time="300000" />
               <remote:async-executor factory="org.infinispan.client.hotrod.impl.async.DefaultAsyncExecutorFactory" />
               <remote:write-behind fail-silently="false" />
               <remote:property name="infinispan.client.hotrod.server_list">{list of 3 servers }</remote:property>
            </remote:remote-store>
         </persistence>
        <expiration lifespan="900000" />
        <memory>
            <object size="10000" strategy="REMOVE" />
        </memory>
      </invalidation-cache>

This is the error :

Error occured while getting cached data with cacheName: user-mapping-cache, key: 77491845>
org.infinispan.commons.CacheException: java.lang.NullPointerException
at org.infinispan.interceptors.impl.InvocationContextInterceptor.rethrowException(InvocationContextInterceptor.java:134)
at org.infinispan.interceptors.impl.InvocationContextInterceptor.lambda$new$0(InvocationContextInterceptor.java:62)
at org.infinispan.interceptors.ExceptionSyncInvocationStage.andExceptionally(ExceptionSyncInvocationStage.java:40)
at org.infinispan.interceptors.BaseAsyncInterceptor.invokeNextAndExceptionally(BaseAsyncInterceptor.java:133)
at org.infinispan.interceptors.impl.InvocationContextInterceptor.visitCommand(InvocationContextInterceptor.java:90)
at org.infinispan.interceptors.impl.AsyncInterceptorChainImpl.invoke(AsyncInterceptorChainImpl.java:244)
at org.infinispan.cache.impl.CacheImpl.get(CacheImpl.java:533)
at org.infinispan.cache.impl.CacheImpl.get(CacheImpl.java:526)
at org.infinispan.cache.impl.AbstractDelegatingCache.get(AbstractDelegatingCache.java:440)
at org.infinispan.cache.impl.EncoderCache.get(EncoderCache.java:713)
at com.companyName.commons.caching.CompanyInfinispanCacheProvider.get(CompanyInfinispanCacheProvider.java:35)
at com.companyName.commons.caching.CompanyCacheService.get(CompanyCacheService.java:60)
at com.companyName.core.branding.CompanyCacheService.get(CompanyCacheService.java:40)
at com.companyName.app.filters.CompanyServletFilter.setBrandingForChannel(CompanyServletFilter.java:170)

Also once it starts, it just keep going. It never stops until the server restarts.