Low-hanging nullable fruit

package.json

@@ -915,11 +915,7 @@
           "description": "Show hints for implicit object creation"
         },
         "omnisharp.path": {
-          "type": [
-            "string",
-            "null"
-          ],
-          "default": null,
+          "type": "string",
           "scope": "machine",
           "description": "Specifies the path to OmniSharp. When left empty the OmniSharp version pinned to the C# Extension is used. This can be the absolute path to an OmniSharp executable, a specific version number, or \"latest\". If a version number or \"latest\" is specified, the appropriate version of OmniSharp will be downloaded on your behalf. Setting \"latest\" is an opt-in into latest beta releases of OmniSharp."
         },
@@ -946,20 +942,12 @@
           "description": "Launch OmniSharp with the globally-installed Mono. If set to \"always\", \"mono\" version 6.4.0 or greater must be available on the PATH. If set to \"auto\", OmniSharp will be launched with \"mono\" if version 6.4.0 or greater is available on the PATH."
         },
         "omnisharp.monoPath": {
-          "type": [
-            "string",
-            "null"
-          ],
-          "default": null,
+          "type": "string",
           "scope": "machine",
           "description": "Specifies the path to a mono installation to use when \"useGlobalMono\" is set to \"always\", instead of the default system one. Example: \"/Library/Frameworks/Mono.framework/Versions/Current\""
         },
         "omnisharp.dotnetPath": {
-          "type": [
-            "string",
-            "null"
-          ],
-          "default": null,
+          "type": "string",
           "scope": "window",
           "description": "Specified the path to a dotnet installation to use when \"useModernNet\" is set to true, instead of the default system one. Example: \"/home/username/mycustomdotnetdirectory\"."
         },
@@ -998,7 +986,6 @@
         },
         "omnisharp.defaultLaunchSolution": {
           "type": "string",
-          "default": null,
           "description": "The name of the default solution used at start up if the repo has multiple solutions. e.g.'MyAwesomeSolution.sln'. Default value is `null` which will cause the first in alphabetical order to be chosen."
         },
         "omnisharp.useEditorFormattingSettings": {
@@ -1063,19 +1050,11 @@
           "description": "Only run analyzers against open files when 'enableRoslynAnalyzers' is true"
         },
         "omnisharp.testRunSettings": {
-          "type": [
-            "string",
-            "null"
-          ],
-          "default": null,
+          "type": "string",
           "description": "Path to the .runsettings file which should be used when running unit tests."
         },
         "razor.plugin.path": {
-          "type": [
-            "string",
-            "null"
-          ],
-          "default": null,
+          "type": "string",
           "scope": "machine",
           "description": "Overrides the path to the Razor plugin dll."
         },
@@ -1090,11 +1069,7 @@
           "description": "Specifies whether to disable Razor language features."
         },
         "razor.languageServer.directory": {
-          "type": [
-            "string",
-            "null"
-          ],
-          "default": null,
+          "type": "string",
           "scope": "machine",
           "description": "Overrides the path to the Razor Language Server directory."
         },

src/common.ts

@@ -61,12 +61,6 @@ export function safeLength<T>(arr: T[] | undefined) {
     return arr ? arr.length : 0;
 }
 
-export async function buildPromiseChain<T, TResult>(array: T[], builder: (item: T) => Promise<TResult>): Promise<TResult> {
-    return array.reduce(
-        async (promise, n) => promise.then(async () => builder(n)),
-        Promise.resolve<TResult>(null));
-}
-
 export async function execChildProcess(command: string, workingDirectory: string = getExtensionPath()): Promise<string> {
     return new Promise<string>((resolve, reject) => {
         cp.exec(command, { cwd: workingDirectory, maxBuffer: 500 * 1024 }, (error, stdout, stderr) => {
@@ -229,4 +223,4 @@ export function isSubfolderOf(subfolder: string, folder: string): boolean {
             }
         }
     }
-}
+}

src/features/diagnosticsProvider.ts

@@ -137,7 +137,7 @@ class DiagnosticsProvider extends AbstractSupport {
 
         this._subscriptions.push(this._validateCurrentDocumentPipe
             .pipe(debounceTime(750))
-            .subscribe(x => this._validateDocument(x)));
+            .subscribe(async document => await this._validateDocument(document)));
 
         this._subscriptions.push(this._validateAllPipe
             .pipe(debounceTime(3000))

src/features/dotnetTest.ts

@@ -194,7 +194,7 @@ export default class TestManager extends AbstractProvider {
 
     private _getRunSettings(filename: string): string | undefined {
         const testSettingsPath = this.optionProvider.GetLatestOptions().testRunSettings;
-        if (!testSettingsPath) {
+        if (testSettingsPath.length === 0) {
             return undefined;
         }
 

src/features/fileOpenCloseProvider.ts

@@ -1,3 +1,8 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
 import { IDisposable } from "../Disposable";
 import { OmniSharpServer } from "../omnisharp/server";
 import * as vscode from 'vscode';

src/omnisharp/LanguageMiddlewareFeature.ts

@@ -22,14 +22,15 @@ type RemapParameterType<M extends keyof RemapApi> = GetRemapType<NonNullable<Rem
 
 export class LanguageMiddlewareFeature implements IDisposable {
     private readonly _middlewares: LanguageMiddleware[];
-    private _registration: IDisposable;
+    private _registration: IDisposable | undefined;
 
     constructor() {
         this._middlewares = [];
     }
 
     public dispose(): void {
-        this._registration.dispose();
+        // this._registration should always be defined, but just in case we never register...
+        this._registration?.dispose();
     }
 
     public register(): void {
@@ -69,4 +70,4 @@ export class LanguageMiddlewareFeature implements IDisposable {
             return original;
         }
     }
-}
+}

src/omnisharp/OmniSharpDotnetResolver.ts

@@ -22,7 +22,7 @@ export class OmniSharpDotnetResolver implements IHostExecutableResolver {
         const dotnet = this.platformInfo.isWindows() ? 'dotnet.exe' : 'dotnet';
         const env = { ...process.env };
 
-        if (options.dotnetPath) {
+        if (options.dotnetPath.length > 0) {
             env['PATH'] = options.dotnetPath + path.delimiter + env['PATH'];
         }
 

src/omnisharp/OmniSharpMonoResolver.ts

@@ -19,7 +19,7 @@ export class OmniSharpMonoResolver implements IHostExecutableResolver {
     private async configureEnvironmentAndGetInfo(options: Options): Promise<HostExecutableInformation> {
         let env = { ...process.env };
         let monoPath: string;
-        if (options.useGlobalMono !== "never" && options.monoPath !== undefined) {
+        if (options.useGlobalMono !== "never" && options.monoPath.length > 0) {
             env['PATH'] = path.join(options.monoPath, 'bin') + path.delimiter + env['PATH'];
             env['MONO_GAC_PREFIX'] = options.monoPath;
             monoPath = options.monoPath;
@@ -40,7 +40,7 @@ export class OmniSharpMonoResolver implements IHostExecutableResolver {
         if (options.useGlobalMono === "always") {
             let isMissing = monoInfo.version === undefined;
             if (isMissing) {
-                const suggestedAction = options.monoPath
+                const suggestedAction = options.monoPath.length > 0
                     ? "Update the \"omnisharp.monoPath\" setting to point to the folder containing Mono's '/bin' folder."
                     : "Ensure that Mono's '/bin' folder is added to your environment's PATH variable.";
                 throw new Error(`Unable to find Mono. ${suggestedAction}`);
@@ -61,4 +61,3 @@ export class OmniSharpMonoResolver implements IHostExecutableResolver {
         return undefined;
     }
 }
-

src/omnisharp/OmnisharpDownloader.ts

@@ -35,9 +35,8 @@ export class OmnisharpDownloader {
                 this.eventStream.post(new InstallationSuccess());
                 return true;
             }
-
-            return false;
         }
+        return false;
     }
 
     public async GetLatestVersion(serverUrl: string, latestVersionFileServerPath: string): Promise<string> {

src/omnisharp/OmnisharpManager.ts

@@ -23,9 +23,9 @@ export class OmnisharpManager {
     }
 
     public async GetOmniSharpLaunchInfo(defaultOmnisharpVersion: string, omnisharpPath: string, useFramework: boolean, serverUrl: string, latestVersionFileServerPath: string, installPath: string, extensionPath: string): Promise<LaunchInfo> {
-        if (!omnisharpPath) {
+        if (omnisharpPath.length === 0) {
             // If omnisharpPath was not specified, return the default path.
-            let basePath = path.resolve(extensionPath, '.omnisharp', defaultOmnisharpVersion + (useFramework ? '' : `-net${modernNetVersion}`));
+            const basePath = path.resolve(extensionPath, '.omnisharp', defaultOmnisharpVersion + (useFramework ? '' : `-net${modernNetVersion}`));
             return this.GetLaunchInfo(this.platformInfo, useFramework, basePath);
         }
 

src/omnisharp/extension.ts

@@ -68,7 +68,7 @@ export async function activate(context: vscode.ExtensionContext, packageJSON: an
     const languageMiddlewareFeature = new LanguageMiddlewareFeature();
     languageMiddlewareFeature.register();
     disposables.add(languageMiddlewareFeature);
-    let localDisposables: CompositeDisposable;
+    let localDisposables: CompositeDisposable | undefined;
     const testManager = new TestManager(optionProvider, server, eventStream, languageMiddlewareFeature);
     const completionProvider = new CompletionProvider(server, languageMiddlewareFeature);
 
@@ -130,7 +130,7 @@ export async function activate(context: vscode.ExtensionContext, packageJSON: an
         if (localDisposables) {
             localDisposables.dispose();
         }
-        localDisposables = null;
+        localDisposables = undefined;
     }));
 
     disposables.add(registerCommands(context, server, platformInfo, eventStream, optionProvider, omnisharpMonoResolver, packageJSON, extensionPath));

src/omnisharp/fileOperationsResponseEditBuilder.ts

@@ -12,7 +12,7 @@ import { toRange2 } from './typeConversion';
 export async function buildEditForResponse(changes: FileOperationResponse[], languageMiddlewareFeature: LanguageMiddlewareFeature, token: vscode.CancellationToken): Promise<boolean> {
     let edit = new vscode.WorkspaceEdit();
 
-    let fileToOpen: Uri = null;
+    let fileToOpen: Uri | undefined;
 
     if (!changes || !Array.isArray(changes) || !changes.length) {
         return true;
@@ -55,7 +55,7 @@ export async function buildEditForResponse(changes: FileOperationResponse[], lan
     // and replaced with a command that can only close the active editor.
     // If files were renamed that weren't the active editor, their tabs will
     // be left open and marked as "deleted" by VS Code
-    return fileToOpen != null
+    return fileToOpen !== undefined
         ? applyEditPromise.then(_ => {
             return vscode.commands.executeCommand("vscode.open", fileToOpen);
         })

src/omnisharp/launcher.ts

@@ -107,7 +107,7 @@ export function resourcesToLaunchTargets(resources: vscode.Uri[]): LaunchTarget[
             let buckets: vscode.Uri[];
 
             if (workspaceFolderToUriMap.has(folder.index)) {
-                buckets = workspaceFolderToUriMap.get(folder.index);
+                buckets = workspaceFolderToUriMap.get(folder.index)!; // Ensured valid via has.
             } else {
                 buckets = [];
                 workspaceFolderToUriMap.set(folder.index, buckets);

src/omnisharp/loggingEvents.ts

@@ -46,7 +46,7 @@ export class OmnisharpInitialisation implements BaseEvent {
 
 export class OmnisharpLaunch implements BaseEvent {
     type = EventType.OmnisharpLaunch;
-    constructor(public hostVersion: string, public hostPath: string, public hostIsMono: boolean, public command: string, public pid: number) { }
+    constructor(public hostVersion: string | undefined, public hostPath: string | undefined, public hostIsMono: boolean, public command: string, public pid: number) { }
 }
 
 export class PackageInstallStart implements BaseEvent {