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/presentation/components/Scripts/View/Tree/NodeContent/Documentation/DocumentationText.vue

@@ -42,7 +42,7 @@ function renderText(docs: readonly string[] | undefined): string {
 }
 
 function renderAsMarkdownListItem(content: string): string {
-  if (!content || content.length === 0) {
+  if (content.length === 0) {
     throw new Error('missing content');
   }
   const lines = content.split(/\r\n|\r|\n/);

src/presentation/components/Scripts/View/Tree/NodeContent/Documentation/MarkdownRenderer.ts

@@ -85,7 +85,8 @@ function removeTrailingExtension(value: string): string {
   if (parts.length === 1) {
     return value;
   }
-  if (parts.at(-1).length > 9) {
+  const extension = parts[parts.length - 1];
+  if (extension.length > 9) {
     return value; // Heuristically web file extension is no longer than 9 chars (e.g. "html")
   }
   return parts.slice(0, -1).join('.');
@@ -115,9 +116,8 @@ function selectMostDescriptiveName(parts: readonly string[]): string | undefined
 }
 
 function isGoodPathPart(part: string): boolean {
-  return part
+  return part.length > 2 // This is often non-human categories like T5 etc.
     && !isDigit(part) // E.g. article numbers, issue numbers
-    && part.length > 2 // This is often non-human categories like T5 etc.
     && !/^index(?:\.\S{0,10}$|$)/.test(part) // E.g. index.html
     && !/^[A-Za-z]{2,4}([_-][A-Za-z]{4})?([_-]([A-Za-z]{2}|[0-9]{3}))$/.test(part) // Locale string e.g. fr-FR
     && !/^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i.test(part) // GUID

src/presentation/components/Scripts/View/Tree/NodeContent/NodeMetadata.ts

@@ -8,6 +8,6 @@ export interface NodeMetadata {
   readonly text: string;
   readonly isReversible: boolean;
   readonly docs: ReadonlyArray<string>;
-  readonly children?: ReadonlyArray<NodeMetadata>;
+  readonly children: ReadonlyArray<NodeMetadata>;
   readonly type: NodeType;
 }

src/presentation/components/Scripts/View/Tree/NodeContent/Reverter/CategoryReverter.ts

@@ -25,10 +25,7 @@ export class CategoryReverter implements IReverter {
 }
 
 function getAllSubScriptReverters(categoryId: number, collection: ICategoryCollection) {
-  const category = collection.findCategory(categoryId);
-  if (!category) {
-    throw new Error(`Category with id "${categoryId}" does not exist`);
-  }
+  const category = collection.getCategory(categoryId);
   const scripts = category.getAllScriptsRecursively();
   return scripts.map((script) => new ScriptReverter(script.id));
 }