Refactor to enforce strictNullChecks

This commit applies `strictNullChecks` to the entire codebase to improve
maintainability and type safety. Key changes include:

- Remove some explicit null-checks where unnecessary.
- Add necessary null-checks.
- Refactor static factory functions for a more functional approach.
- Improve some test names and contexts for better debugging.
- Add unit tests for any additional logic introduced.
- Refactor `createPositionFromRegexFullMatch` to its own function as the
  logic is reused.
- Prefer `find` prefix on functions that may return `undefined` and
  `get` prefix for those that always return a value.

tests/unit/domain/ProjectInformation.spec.ts

@@ -159,7 +159,7 @@ describe('ProjectInformation', () => {
         expect(actual).to.equal(expected);
       });
     }
-    it('should throw an error when provided with an invalid operating system', () => {
+    describe('should throw an error when provided with an invalid operating system', () => {
       // arrange
       const sut = new ProjectInformationBuilder()
         .build();
@@ -168,7 +168,6 @@ describe('ProjectInformation', () => {
       // assert
       new EnumRangeTestRunner(act)
         .testOutOfRangeThrows()
-        .testAbsentValueThrows()
         .testInvalidValueThrows(OperatingSystem.KaiOS, `Unsupported os: ${OperatingSystem[OperatingSystem.KaiOS]}`);
     });
   });