Cleaning up implementations code lens

- Make async
- extract some methods

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

@@ -16,44 +16,57 @@ 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 =>
+						// Only take first line on implementation: https://github.com/Microsoft/vscode/issues/23924
+						new vscode.Location(this.client.toResource(reference.file),
+							reference.start.line === reference.end.line
+								? typeConverters.Range.fromTextSpan(reference)
+								: new vscode.Range(
+									reference.start.line - 1, reference.start.offset - 1,
+									reference.start.line, 0)))
+					// Exclude original from implementations
+					.filter(location =>
+						!(location.uri.toString() === codeLens.document.toString() &&
+							location.range.start.line === codeLens.range.start.line &&
+							location.range.start.character === codeLens.range.start.character));
+
+				codeLens.command = this.getCommand(locations, codeLens);
+				return codeLens;
 			}
+		} catch {
+			// noop
+		}
 
-			const locations = response.body
-				.map(reference =>
-					// Only take first line on implementation: https://github.com/Microsoft/vscode/issues/23924
-					new vscode.Location(this.client.toResource(reference.file),
-						reference.start.line === reference.end.line
-							? typeConverters.Range.fromTextSpan(reference)
-							: new vscode.Range(
-								reference.start.line - 1, reference.start.offset - 1,
-								reference.start.line, 0)))
-				// Exclude original from implementations
-				.filter(location =>
-					!(location.uri.toString() === codeLens.document.toString() &&
-						location.range.start.line === codeLens.range.start.line &&
-						location.range.start.character === codeLens.range.start.character));
+		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]
+		};
+	}
 
-			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]
-			};
-			return codeLens;
-		}).catch(() => {
-			codeLens.command = {
-				title: localize('implementationsErrorLabel', 'Could not determine implementations'),
-				command: ''
-			};
-			return codeLens;
-		});
+	private getTitle(locations: vscode.Location[]): string {
+		return locations.length === 1
+			? localize('oneImplementationLabel', '1 implementation')
+			: localize('manyImplementationLabel', '{0} implementations', locations.length);
 	}
 
 	protected extractSymbol(