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/checks/desktop-runtime-errors/check-desktop-runtime-errors/utils/platform.ts

@@ -15,7 +15,7 @@ const NODE_PLATFORM_MAPPINGS: {
   [SupportedPlatform.Windows]: 'win32',
 };
 
-function findCurrentPlatform(): SupportedPlatform | undefined {
+function getCurrentPlatform(): SupportedPlatform | never {
   const nodePlatform = platform();
 
   for (const key of Object.keys(NODE_PLATFORM_MAPPINGS)) {
@@ -28,4 +28,4 @@ function findCurrentPlatform(): SupportedPlatform | undefined {
   return die(`Unsupported platform: ${nodePlatform}`);
 }
 
-export const CURRENT_PLATFORM: SupportedPlatform = findCurrentPlatform();
+export const CURRENT_PLATFORM: SupportedPlatform = getCurrentPlatform();