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.

src/infrastructure/EnvironmentVariables/EnvironmentVariablesValidator.ts

@@ -2,9 +2,6 @@ import { IEnvironmentVariables } from './IEnvironmentVariables';
 
 /* Validation is externalized to keep the environment objects simple */
 export function validateEnvironmentVariables(environment: IEnvironmentVariables): void {
-  if (!environment) {
-    throw new Error('missing environment');
-  }
   const keyValues = capturePropertyValues(environment);
   if (!Object.keys(keyValues).length) {
     throw new Error('Unable to capture key/value pairs');
@@ -30,7 +27,7 @@ function getKeysMissingValues(keyValuePairs: Record<string, unknown>): string[]
  * Necessary because code transformations can make class getters non-enumerable during bundling.
  * This ensures that even if getters are non-enumerable, their values are still captured and used.
  */
-function capturePropertyValues(instance: unknown): Record<string, unknown> {
+function capturePropertyValues(instance: object): Record<string, unknown> {
   const obj: Record<string, unknown> = {};
   const descriptors = Object.getOwnPropertyDescriptors(instance.constructor.prototype);