fix: added null check before value conversion to avoid panic

[Rchanger]

Closes #1019

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Merging #1020 (c8db224) into master (eaf5927) will decrease coverage by 0.03%.
The diff coverage is 60.00%.

@@            Coverage Diff             @@
##           master    #1020      +/-   ##
==========================================
- Coverage   78.22%   78.18%   -0.04%     
==========================================
  Files         237      237              
  Lines        6292     6299       +7     
==========================================
+ Hits         4922     4925       +3     
- Misses       1067     1069       +2     
- Partials      303      305       +2     

Impacted Files	Coverage Δ
.../iac-providers/terraform/commons/cty-converters.go	76.92% <0.00%> (-3.08%)	⬇️
...ders/terraform/commons/extract-container-images.go	78.63% <75.00%> (-0.84%)	⬇️