[#9120] Backport: fix npe bug in mongo plugin

[jaehong-kim]

#9120

[codecov]

Codecov Report

Merging #9121 (c4247c5) into 2.4.x (a0d9abb) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##              2.4.x    #9121      +/-   ##
============================================
- Coverage     40.20%   40.19%   -0.01%     
+ Complexity    11729    11725       -4     
============================================
  Files          3285     3285              
  Lines         89460    89461       +1     
  Branches      10016    10016              
============================================
- Hits          35967    35961       -6     
- Misses        50428    50434       +6     
- Partials       3065     3066       +1     

Impacted Files	Coverage Δ
...interceptor/MongoClientConstructorInterceptor.java	0.00% <0.00%> (ø)
...pinpoint/rpc/ChannelWriteFailListenableFuture.java	42.85% <0.00%> (-28.58%)	⬇️
...vercorp/pinpoint/rpc/packet/ClientClosePacket.java	46.66% <0.00%> (-6.67%)	⬇️
...orp/pinpoint/profiler/sender/NioUDPDataSender.java	62.82% <0.00%> (-5.13%)	⬇️
...rc/main/java/com/navercorp/pinpoint/test/Item.java	68.51% <0.00%> (-3.71%)	⬇️
...java/com/navercorp/pinpoint/rpc/DefaultFuture.java	75.22% <0.00%> (-1.84%)	⬇️
...orp/pinpoint/rpc/server/DefaultPinpointServer.java	80.65% <0.00%> (-0.42%)	⬇️
...point/rpc/client/DefaultPinpointClientHandler.java	71.83% <0.00%> (+1.40%)	⬆️
...pc/server/LoggingServerMessageListenerFactory.java	90.47% <0.00%> (+9.52%)	⬆️

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