Ensure global singleton registries are truly global

...even when the decoders bundle is doubly-included in production builds
for some reason.

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## [Unreleased]
 
+- Ensure the global singleton registries are truly global, even if somehow the bundler
+  might have included multiple copies of decoders (CJS and ESM) in the same bundle.
 - Use `node16` module resolution setting (recommended setting for libraries that run in
   both browsers and Node environments)
 

src/core/Decoder.ts

@@ -334,7 +334,9 @@ export function define<T>(fn: AcceptanceFn<T>): Decoder<T> {
 }
 
 /** @internal */
-const _register = new WeakSet<Decoder<unknown>>();
+const kDecoderRegistry = Symbol.for('decoders.kDecoderRegistry');
+const _register: WeakSet<Decoder<unknown>> = ((globalThis as any)[kDecoderRegistry] ??=
+  new WeakSet());
 
 /** @internal */
 function brand<D extends Decoder<unknown>>(decoder: D): D {

src/core/annotate.ts

@@ -1,6 +1,8 @@
 import { isPojo } from '~/lib/utils.js';
 
-const _register = new WeakSet<Annotation>();
+const kAnnotationRegistry = Symbol.for('decoders.kAnnotationRegistry');
+const _register: WeakSet<Annotation> = ((globalThis as any)[kAnnotationRegistry] ??=
+  new WeakSet());
 
 export interface ObjectAnnotation {
   readonly type: 'object';