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/Code/CodeButtons/Save/Instructions/Data/InstructionsBuilder.ts

@@ -15,13 +15,11 @@ export class InstructionsBuilder {
   }
 
   public withStep(stepBuilder: InstructionStepBuilderType) {
-    if (!stepBuilder) { throw new Error('missing stepBuilder'); }
     this.stepBuilders.push(stepBuilder);
     return this;
   }
 
   public build(data: IInstructionsBuilderData): IInstructionListData {
-    if (!data) { throw new Error('missing data'); }
     return {
       operatingSystem: this.os,
       steps: this.stepBuilders.map((stepBuilder) => stepBuilder(data)),

src/presentation/components/Code/CodeButtons/Save/Instructions/InstructionList.vue

@@ -86,12 +86,9 @@ export default defineComponent({
       () => info.getDownloadUrl(OperatingSystem.macOS),
     );
 
-    const osName = computed<string>(() => {
-      if (!props.data) {
-        throw new Error('missing data');
-      }
-      return renderOsName(props.data.operatingSystem);
-    });
+    const osName = computed<string>(
+      () => renderOsName(props.data.operatingSystem),
+    );
 
     return {
       appName,

src/presentation/components/Code/CodeButtons/Save/Instructions/InstructionListDataFactory.ts

@@ -9,15 +9,11 @@ const builders = new Map<OperatingSystem, InstructionsBuilder>([
   [OperatingSystem.Linux, new LinuxInstructionsBuilder()],
 ]);
 
-export function hasInstructions(os: OperatingSystem) {
-  return builders.has(os);
-}
-
 export function getInstructions(
   os: OperatingSystem,
   fileName: string,
-): IInstructionListData {
+): IInstructionListData | undefined {
   return builders
     .get(os)
-    .build({ fileName });
+    ?.build({ fileName });
 }