Refactor error handling for empty JSON and XML payloads

[TharmiganK]

Purpose

$Subject

Part of: ballerina-platform/ballerina-library#8475

Examples

Checklist

• Linked to an issue
• Updated the changelog
• Added tests
• Updated the spec
• Checked native-image compatibility

[codecov]

Codecov Report

❌ Patch coverage is 55.55556% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.09%. Comparing base (9c14c6f) to head (629962a).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...n/java/io/ballerina/stdlib/mime/util/MimeUtil.java	38.46%	15 Missing and 1 partial ⚠️

❌ Your project status has failed because the head coverage (76.09%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #567      +/-   ##
============================================
- Coverage     76.89%   76.09%   -0.81%     
  Complexity        9        9              
============================================
  Files            21       21              
  Lines          1212     1238      +26     
  Branches        184      186       +2     
============================================
+ Hits            932      942      +10     
- Misses          198      213      +15     
- Partials         82       83       +1     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud