fix issue#163: nil reference when paring the tries

[alonlong]

add the error handler for paring the tries

[petethepig]

Looks good, thanks for fixing this @alonlong . This closes #163

[codecov]

Codecov Report

Merging #194 (bce5f83) into main (555f765) will increase coverage by 0.06%.
The diff coverage is 33.34%.

@@            Coverage Diff             @@
##             main     #194      +/-   ##
==========================================
+ Coverage   57.29%   57.35%   +0.06%     
==========================================
  Files          73       73              
  Lines        2938     2942       +4     
==========================================
+ Hits         1683     1687       +4     
+ Misses       1112     1110       -2     
- Partials      143      145       +2     

Impacted Files	Coverage Δ
pkg/convert/parser.go	62.80% <33.34%> (-3.06%)	⬇️
pkg/server/ingest.go	63.39% <33.34%> (-1.83%)	⬇️
pkg/agent/session.go	67.22% <0.00%> (+3.28%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 555f765...bce5f83. Read the comment docs.