Cleaning up implementations code lens

- Make async
- extract some methods

extensions/typescript-language-features/src/features/implementationsCodeLens.ts

@@ -16,13 +16,15 @@ const localize = nls.loadMessageBundle();
 
 export default class TypeScriptImplementationsCodeLensProvider extends TypeScriptBaseCodeLensProvider {
 
-	public resolveCodeLens(inputCodeLens: vscode.CodeLens, token: vscode.CancellationToken): Promise<vscode.CodeLens> {
+	public async resolveCodeLens(
+		inputCodeLens: vscode.CodeLens,
+		token: vscode.CancellationToken,
+	): Promise<vscode.CodeLens> {
 		const codeLens = inputCodeLens as ReferencesCodeLens;
 		const args = typeConverters.Position.toFileLocationRequestArgs(codeLens.file, codeLens.range.start);
-		return this.client.execute('implementation', args, token).then(response => {
-			if (!response || !response.body) {
-				throw codeLens;
-			}
+		try {
+			const response = await this.client.execute('implementation', args, token);
+			if (response && response.body) {
 
 				const locations = response.body
 					.map(reference =>
@@ -39,21 +41,32 @@ export default class TypeScriptImplementationsCodeLensProvider extends TypeScrip
 							location.range.start.line === codeLens.range.start.line &&
 							location.range.start.character === codeLens.range.start.character));
 
-			codeLens.command = {
-				title: locations.length === 1
-					? localize('oneImplementationLabel', '1 implementation')
-					: localize('manyImplementationLabel', '{0} implementations', locations.length),
-				command: locations.length ? 'editor.action.showReferences' : '',
-				arguments: [codeLens.document, codeLens.range.start, locations]
-			};
+				codeLens.command = this.getCommand(locations, codeLens);
 				return codeLens;
-		}).catch(() => {
+			}
+		} catch {
+			// noop
+		}
+
 		codeLens.command = {
 			title: localize('implementationsErrorLabel', 'Could not determine implementations'),
 			command: ''
 		};
 		return codeLens;
-		});
+	}
+
+	private getCommand(locations: vscode.Location[], codeLens: ReferencesCodeLens): vscode.Command | undefined {
+		return {
+			title: this.getTitle(locations),
+			command: locations.length ? 'editor.action.showReferences' : '',
+			arguments: [codeLens.document, codeLens.range.start, locations]
+		};
+	}
+
+	private getTitle(locations: vscode.Location[]): string {
+		return locations.length === 1
+			? localize('oneImplementationLabel', '1 implementation')
+			: localize('manyImplementationLabel', '{0} implementations', locations.length);
 	}
 
 	protected extractSymbol(