Setup eslint and enforce rules

src/service/FakeCanonical.ts

@@ -1,11 +1,11 @@
-import {Canonical} from "./Canonical";
+import {Canonical} from './Canonical'
 
 /**
  * Canonical class used for faking canonical units. Here, the canonical resolver
  * is registered with the global service, but no files are loaded from the filesystem.
  */
 export class FakeCanonical<T> extends Canonical<T> {
-    public async up() {
+    public async up(): Promise<void> {
         this.canon.registerCanonical(this)
     }
 }