Setup eslint and enforce rules

src/util/cache/Cache.ts

@@ -1,4 +1,4 @@
-import {Awaitable} from "../support/types"
+import {Awaitable} from '../support/types'
 
 /**
  * Abstract interface class for a cached object.

src/util/cache/InMemCache.ts

@@ -20,22 +20,28 @@ export class InMemCache extends Cache {
      */
     protected items: Collection<InMemCacheItem> = new Collection<InMemCacheItem>()
 
-    public async fetch(key: string) {
+    public async fetch(key: string): Promise<string | undefined> {
         const item = this.items.firstWhere('key', '=', key)
-        if ( item ) return item.item
+        if ( item ) {
+            return item.item
+        }
     }
 
-    public async put(key: string, item: string) {
+    public async put(key: string, item: string): Promise<void> {
         const existing = this.items.firstWhere('key', '=', key)
-        if ( existing ) existing.item = item
-        else this.items.push({ key, item })
+        if ( existing ) {
+            existing.item = item
+        } else {
+            this.items.push({ key,
+                item })
+        }
     }
 
-    public async has(key: string) {
+    public async has(key: string): Promise<boolean> {
         return this.items.where('key', '=', key).length > 0
     }
 
-    public async drop(key: string) {
+    public async drop(key: string): Promise<void> {
         this.items = this.items.whereNot('key', '=', key)
     }
 }