diff --git a/src/common/catalog/catalog-category-registry.ts b/src/common/catalog/catalog-category-registry.ts
index 68e3e811b8..a0319d773b 100644
--- a/src/common/catalog/catalog-category-registry.ts
+++ b/src/common/catalog/catalog-category-registry.ts
@@ -20,7 +20,7 @@
  */
 
 import { action, computed, observable } from "mobx";
-import { Disposer, ExtendedMap, StrictMap } from "../utils";
+import { Disposer, ExtendedMap } from "../utils";
 import { CatalogCategory, CatalogEntityData, CatalogEntityKindData } from "./catalog-entity";
 
 export class CatalogCategoryRegistry {
@@ -33,10 +33,13 @@ export class CatalogCategoryRegistry {
   }
 
   @computed private get groupKindLookup(): Map<string, Map<string, CatalogCategory>> {
-    const res = new ExtendedMap<string, StrictMap<string, CatalogCategory>>(StrictMap.new);
+    // ExtendedMap has the convenience methods `getOrInsert` and `strictSet`
+    const res = new ExtendedMap<string, ExtendedMap<string, CatalogCategory>>();
 
     for (const category of this.categories) {
-      res.getOrDefault(category.spec.group).strictSet(category.spec.names.kind, category);
+      res
+        .getOrInsert(category.spec.group, ExtendedMap.new)
+        .strictSet(category.spec.names.kind, category);
     }
 
     return res;
diff --git a/src/common/utils/extended-map.ts b/src/common/utils/extended-map.ts
index 460e716f1c..c8b7ff4c65 100644
--- a/src/common/utils/extended-map.ts
+++ b/src/common/utils/extended-map.ts
@@ -21,13 +21,29 @@
 
 import { action, IEnhancer, IObservableMapInitialValues, ObservableMap } from "mobx";
 
-export class StrictMap<K, V> extends Map<K, V> {
-  static new<K, V>(): StrictMap<K, V> {
-    return new StrictMap();
+export class ExtendedMap<K, V> extends Map<K, V> {
+  static new<K, V>(entries?: readonly (readonly [K, V])[] | null): ExtendedMap<K, V> {
+    return new ExtendedMap<K, V>(entries);
   }
 
   /**
+   * Get the value behind `key`. If it was not pressent, first insert the value returned by `getVal`
+   * @param key The key to insert into the map with
+   * @param getVal A function that returns a new instance of `V`.
+   * @returns The value in the map
+   */
+  getOrInsert(key: K, getVal: () => V): V {
+    if (this.has(key)) {
+      return this.get(key);
+    }
+
+    return this.set(key, getVal()).get(key);
+  }
+
+  /**
+   * Set the value associated with `key` iff there was not a previous value
    * @throws if `key` already in map
+   * @returns `this` so that `strictSet` can be chained
    */
   strictSet(key: K, val: V): this {
     if (this.has(key)) {
@@ -36,39 +52,17 @@ export class StrictMap<K, V> extends Map<K, V> {
 
     return this.set(key, val);
   }
-}
 
-export class ExtendedMap<K, V> extends Map<K, V> {
-  static new<K, MK, MV>(): ExtendedMap<K, Map<MK, MV>> {
-    return new ExtendedMap<K, Map<MK, MV>>(() => new Map<MK, MV>());
-  }
-
-  constructor(protected getDefault: () => V, entries?: readonly (readonly [K, V])[] | null) {
-    super(entries);
-  }
-
-  getOrInsert(key: K, val: V): V {
-    if (this.has(key)) {
-      return this.get(key);
+  /**
+   * Get the value associated with `key`
+   * @throws if `key` did not a value associated with it
+   */
+  strictGet(key: K): V {
+    if (!this.has(key)) {
+      throw new TypeError("key not in map");
     }
 
-    return this.set(key, val).get(key);
-  }
-
-  getOrInsertWith(key: K, getVal: () => V): V {
-    if (this.has(key)) {
-      return this.get(key);
-    }
-
-    return this.set(key, getVal()).get(key);
-  }
-
-  getOrDefault(key: K): V {
-    if (this.has(key)) {
-      return this.get(key);
-    }
-
-    return this.set(key, this.getDefault()).get(key);
+    return this.get(key);
   }
 }