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/CodeRunButton.vue

@@ -40,7 +40,7 @@ export default defineComponent({
 function getCanRunState(
   selectedOs: OperatingSystem,
   isDesktopVersion: boolean,
-  hostOs: OperatingSystem,
+  hostOs: OperatingSystem | undefined,
 ): boolean {
   const isRunningOnSelectedOs = selectedOs === hostOs;
   return isDesktopVersion && isRunningOnSelectedOs;

src/presentation/components/Code/CodeButtons/Save/CodeSaveButton.vue

@@ -21,11 +21,10 @@ import ModalDialog from '@/presentation/components/Shared/Modal/ModalDialog.vue'
 import { IReadOnlyCategoryCollectionState } from '@/application/Context/State/ICategoryCollectionState';
 import { ScriptingLanguage } from '@/domain/ScriptingLanguage';
 import { IScriptingDefinition } from '@/domain/IScriptingDefinition';
-import { OperatingSystem } from '@/domain/OperatingSystem';
 import IconButton from '../IconButton.vue';
 import InstructionList from './Instructions/InstructionList.vue';
 import { IInstructionListData } from './Instructions/InstructionListData';
-import { getInstructions, hasInstructions } from './Instructions/InstructionListDataFactory';
+import { getInstructions } from './Instructions/InstructionListDataFactory';
 
 export default defineComponent({
   components: {
@@ -39,7 +38,7 @@ export default defineComponent({
 
     const areInstructionsVisible = ref(false);
     const fileName = computed<string>(() => buildFileName(currentState.value.collection.scripting));
-    const instructions = computed<IInstructionListData | undefined>(() => getDownloadInstructions(
+    const instructions = computed<IInstructionListData | undefined>(() => getInstructions(
       currentState.value.collection.os,
       fileName.value,
     ));
@@ -59,16 +58,6 @@ export default defineComponent({
   },
 });
 
-function getDownloadInstructions(
-  os: OperatingSystem,
-  fileName: string,
-): IInstructionListData | undefined {
-  if (!hasInstructions(os)) {
-    return undefined;
-  }
-  return getInstructions(os, fileName);
-}
-
 function saveCodeToDisk(fileName: string, state: IReadOnlyCategoryCollectionState) {
   const content = state.code.current;
   const type = getType(state.collection.scripting.language);

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 });
 }

src/presentation/components/Code/TheCodeArea.vue

@@ -70,7 +70,7 @@ export default defineComponent({
 
     function updateCode(code: string, language: ScriptingLanguage) {
       const innerCode = code || getDefaultCode(language);
-      editor.setValue(innerCode, 1);
+      editor?.setValue(innerCode, 1);
     }
 
     function handleCodeChange(event: ICodeChangedEvent) {
@@ -96,7 +96,7 @@ export default defineComponent({
       if (!currentMarkerId) {
         return;
       }
-      editor.session.removeMarker(currentMarkerId);
+      editor?.session.removeMarker(currentMarkerId);
       currentMarkerId = undefined;
     }
 
@@ -115,7 +115,7 @@ export default defineComponent({
 
     function highlight(startRow: number, endRow: number) {
       const AceRange = ace.require('ace/range').Range;
-      currentMarkerId = editor.session.addMarker(
+      currentMarkerId = editor?.session.addMarker(
         new AceRange(startRow, 0, endRow, 0),
         'code-area__highlight',
         'fullLine',
@@ -123,8 +123,11 @@ export default defineComponent({
     }
 
     function scrollToLine(row: number) {
-      const column = editor.session.getLine(row).length;
-      editor.gotoLine(row, column, true);
+      const column = editor?.session.getLine(row).length;
+      if (column === undefined) {
+        return;
+      }
+      editor?.gotoLine(row, column, true);
     }
 
     return {