assert: fix assert.fail() stack

This makes sure the error message visible in the error stack created
when using `assert.fail()` without any arguments or the message set
to `undefined` or `null` as only argument.
That was masked before due to other changes.

PR-URL: https://github.com/nodejs/node/pull/27525
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

lib/assert.js

@@ -92,9 +92,10 @@ function innerFail(obj) {
 function fail(actual, expected, message, operator, stackStartFn) {
   const argsLen = arguments.length;
 
-  let internalMessage;
-  if (argsLen === 0) {
-    internalMessage = 'Failed';
+  let internalMessage = false;
+  if (actual == null && argsLen <= 1) {
+    internalMessage = true;
+    message = 'Failed';
   } else if (argsLen === 1) {
     message = actual;
     actual = undefined;
@@ -118,14 +119,11 @@ function fail(actual, expected, message, operator, stackStartFn) {
     actual,
     expected,
     operator: operator === undefined ? 'fail' : operator,
-    stackStartFn: stackStartFn || fail
+    stackStartFn: stackStartFn || fail,
+    message
   };
-  if (message !== undefined) {
-    errArgs.message = message;
-  }
   const err = new AssertionError(errArgs);
   if (internalMessage) {
-    err.message = internalMessage;
     err.generatedMessage = true;
   }
   throw err;

test/parallel/test-assert-fail.js

@@ -13,7 +13,8 @@ assert.throws(
     operator: 'fail',
     actual: undefined,
     expected: undefined,
-    generatedMessage: true
+    generatedMessage: true,
+    stack: /Failed/
   }
 );