warn of action clashes

src/Updux.js

@@ -14,10 +14,21 @@ export class Updux {
         this.#localInitial = config.initial ?? {};
         this.#subduxes = config.subduxes ?? {};
 
-        this.#actions = R.mergeAll([
-            config.actions ?? {},
-            ...Object.values(this.#subduxes).map(R.prop('actions')),
-        ]);
+        this.#actions = { ...config.actions };
+        Object.entries(this.#subduxes).forEach( ([slice,sub]) => this.#addSubduxActions(slice,sub) )
+    }
+
+    #addSubduxActions(_slice, subdux) {
+        if( ! subdux.actions ) return;
+        // TODO action 'blah' defined multiple times: <where>
+        Object.entries( subdux.actions ).forEach( ([action,gen]) => {
+            if( this.#actions[action] ) {
+                if( this.#actions[action] === gen ) return;
+                throw new Error(`action '${action}' already defined`);
+            }
+
+            this.#actions[action] = gen;
+        });
     }
 
     get actions() {

src/actions.test.js

@@ -51,3 +51,19 @@ test('subduxes actions', () => {
     expect(foo.actions).toHaveProperty('foo');
     expect(foo.actions).toHaveProperty('bar');
 });
+
+test('throw if double action', () => {
+    expect( () => new Updux({
+        actions: {
+            foo: action('foo'),
+        },
+        subduxes: {
+            beta: {
+                actions: {
+                    foo: action('foo'),
+                },
+            },
+        },
+    }) ).toThrow(/action 'foo' already defined/);
+
+});