return an empty API

Extension/src/cppTools1.ts

@@ -4,7 +4,7 @@
  * ------------------------------------------------------------------------------------------ */
 'use strict';
 
-import { CustomConfigurationProvider, Version, CppToolsApi } from 'vscode-cpptools';
+import { CustomConfigurationProvider, Version, CppToolsApi, CppToolsExtension } from 'vscode-cpptools';
 import { CppToolsTestApi, CppToolsTestHook, CppToolsTestExtension } from 'vscode-cpptools/out/testApi';
 import { CppTools } from './cppTools';
 
@@ -63,3 +63,35 @@ export class CppTools1 implements CppToolsTestApi, CppToolsTestExtension {
         return this.BackupApi.getTestHook();
     }
 }
+
+/**
+ * This is an empty implementation of the API. Used when the extension is activated on
+ * an unsupported platform.
+ */
+export class NullCppTools implements CppToolsApi, CppToolsExtension {
+    private version: Version;
+
+    getApi(version: Version): CppToolsApi {
+        this.version = version;
+        return this;
+    }
+    
+    getVersion(): Version {
+        return this.version;
+    }
+
+    registerCustomConfigurationProvider(provider: CustomConfigurationProvider): void {
+    }
+
+    notifyReady(provider: CustomConfigurationProvider): void {
+    }
+
+    didChangeCustomConfiguration(provider: CustomConfigurationProvider): void {
+    }
+
+    didChangeCustomBrowseConfiguration(provider: CustomConfigurationProvider): void {
+    }
+
+    dispose(): void {
+    }
+}

Extension/src/main.ts

@@ -20,7 +20,7 @@ import { PackageManager, PackageManagerError, IPackage } from './packageManager'
 import { PersistentState } from './LanguageServer/persistentState';
 import { getInstallationInformation, InstallationInformation, setInstallationStage, setInstallationType, InstallationType } from './installationInformation';
 import { Logger, getOutputChannelLogger, showOutputChannel } from './logger';
-import { CppTools1 } from './cppTools1';
+import { CppTools1, NullCppTools } from './cppTools1';
 
 const releaseNotesVersion: number = 5;
 const cppTools: CppTools1 = new CppTools1();
@@ -37,7 +37,7 @@ export async function activate(context: vscode.ExtensionContext): Promise<CppToo
     }
     if (errMsg) {
         vscode.window.showErrorMessage(errMsg);
-        return;
+        return new NullCppTools();
     }
 
     util.setExtensionContext(context);