assert: fix deepStrictEqual on errors when cause is not undefined

PR-URL: https://github.com/nodejs/node/pull/55406
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/internal/assert/assertion_error.js

@@ -15,6 +15,8 @@ const {
   StringPrototypeSplit,
 } = primordials;
 
+const { isError } = require('internal/util');
+
 const { inspect } = require('internal/util/inspect');
 const colors = require('internal/util/colors');
 const { validateObject } = require('internal/validators');
@@ -47,6 +49,15 @@ function copyError(source) {
     __proto__: null,
     value: source.message,
   });
+  if (source.cause !== undefined) {
+    let cause = source.cause;
+
+    if (isError(cause)) {
+      cause = copyError(cause);
+    }
+
+    ObjectDefineProperty(target, 'cause', { __proto__: null, value: cause });
+  }
   return target;
 }