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/text.ts

@@ -15,6 +15,11 @@ export function splitTextIntoLines(text: string): string[] {
     .split(/[\r\n]+/);
 }
 
+export function filterEmpty(texts: readonly (string | undefined | null)[]): string[] {
+  return texts
+    .filter((title): title is string => Boolean(title));
+}
+
 function validateText(text: string): void {
   if (typeof text !== 'string') {
     throw new Error(`text is not a string. It is: ${typeof text}\n${text}`);