fix #1500

[kimmking]

add exception fields processing

[codecov-io]

Codecov Report

Merging #1506 into master will decrease coverage by <.01%.
The diff coverage is 83.33%.

@@             Coverage Diff              @@
##             master    #1506      +/-   ##
============================================
- Coverage     82.79%   82.78%   -0.01%     
+ Complexity     6026     6025       -1     
============================================
  Files           136      136              
  Lines         22043    22049       +6     
  Branches       5034     5034              
============================================
+ Hits          18250    18253       +3     
  Misses         2552     2552              
- Partials       1241     1244       +3

Impacted Files	Coverage Δ	Complexity Δ
...son/parser/deserializer/ThrowableDeserializer.java	92% <83.33%> (-0.56%)	32 <0> (ø)
...com/alibaba/fastjson/parser/JSONReaderScanner.java	72.61% <0%> (-1.28%)	44% <0%> (-1%)
...m/alibaba/fastjson/serializer/SerializeWriter.java	89.05% <0%> (-0.09%)	371% <0%> (-1%)
...ava/com/alibaba/fastjson/parser/JSONLexerBase.java	71.52% <0%> (+0.03%)	785% <0%> (+1%)	⬆️

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[wenshao]

ThrowableDeserializer是每个class一个的，可以在实例级别对Field做缓存么？从反射中获取field会很慢的

[kimmking]

可以考虑，目前这么处理是因为：一般的逻辑是走不到新加的处理里面来的。