Fix null property access at getBaseClassDependencyCount

[notaphplover]

Description

• Fixed unexpected property access on null valeus when running planning checks on injected base classes.
• Fixed ESM sourcemap links.

Related Issue

#1664

How Has This Been Tested?

• Tests run successfully.
• Sourcemaps target right ts files.

Types of changes

• Updated docs / Refactor code / Added a tests case (non-breaking change)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have updated the changelog.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.09%. Comparing base (f7dd2c8) to head (582c3b3).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1665   +/-   ##
=======================================
  Coverage   99.09%   99.09%           
=======================================
  Files          51       52    +1     
  Lines        1327     1332    +5     
  Branches      180      180           
=======================================
+ Hits         1315     1320    +5     
  Misses         11       11           
  Partials        1        1           

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