added guard code to avoid NPE in assignCategory and assignAuthors functions

[jitender94136]

No description provided.

[codecov]

Codecov Report

Merging #314 (e0a9607) into master (6d004b2) will decrease coverage by 0.10%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master     #314      +/-   ##
============================================
- Coverage     78.10%   78.00%   -0.11%     
- Complexity      493      495       +2     
============================================
  Files            89       89              
  Lines          1544     1546       +2     
  Branches        128      128              
============================================
  Hits           1206     1206              
  Misses          269      269              
- Partials         69       71       +2     

Impacted Files	Coverage Δ
.../java/com/aventstack/extentreports/ExtentTest.java	91.03% <0.00%> (-1.28%)	⬇️

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[anshooarora]

Thank you for including this guardrail. Although, both can be used to the same effect, the following method is what has been used throughout this library. Can you please make this change and resend your PR?

x.trim().length() != 0

would be:

!x.trim().isEmpty()