Filter invalid matchers before extending expect

src/index.ts

@@ -10,6 +10,17 @@ const expect: typeof expectPatched = instrument(
   { intercept: (_method, path) => path[0] !== 'expect' }
 ).expect;
 
-expect.extend(matchers);
+// @TODO: This should be reverted once https://github.com/testing-library/jest-dom/pull/438 is merged
+// Some bundlers include an undefined `default` in the namespace import,
+// or __esmodule (a boolean) which cause expect.extend to throw.
+const validMatchers = { ...matchers };
+Object.keys(validMatchers).forEach((matcherName) => {
+  const matcher = validMatchers[matcherName];
+  if (typeof matcher === 'undefined' || typeof matcher === 'boolean') {
+    delete validMatchers[matcherName];
+  }
+});
+
+expect.extend(validMatchers);
 
 export { expect, jest };