fix: Have AsyncHandlers only check what is necessary

src/ldp/http/BasicTargetExtractor.ts

@@ -10,16 +10,17 @@ import { TargetExtractor } from './TargetExtractor';
  * TODO: input requires more extensive cleaning/parsing based on headers (see #22).
  */
 export class BasicTargetExtractor extends TargetExtractor {
-  public async canHandle(input: HttpRequest): Promise<void> {
+  public async canHandle(): Promise<void> {
+    // Can handle all URLs
+  }
+
+  public async handle(input: HttpRequest): Promise<ResourceIdentifier> {
     if (!input.url) {
       throw new Error('Missing URL.');
     }
     if (!input.headers.host) {
       throw new Error('Missing host.');
     }
-  }
-
-  public async handle(input: HttpRequest): Promise<ResourceIdentifier> {
     const isHttps = input.connection && (input.connection as TLSSocket).encrypted;
     const url = format({
       protocol: `http${isHttps ? 's' : ''}`,