util: serialize falsy cause values while inspecting errors

Signed-off-by: Ruben Bridgewater <ruben@bridgewater.de>

PR-URL: #41097
Fixes: #41096
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>

lib/internal/util/inspect.js

@@ -1282,7 +1282,8 @@ function formatError(err, constructor, tag, ctx, keys) {
 
   removeDuplicateErrorKeys(ctx, keys, err, stack);
 
-  if (err.cause && (keys.length === 0 || !keys.includes('cause'))) {
+  if (err.cause !== undefined &&
+      (keys.length === 0 || !keys.includes('cause'))) {
     keys.push('cause');
   }
 

test/parallel/test-util-inspect.js

@@ -660,6 +660,16 @@ assert.strictEqual(util.inspect(-5e-324), '-5e-324');
   assert(ex.includes('[message]'));
 }
 
+{
+  const falsyCause1 = new Error('', { cause: false });
+  delete falsyCause1.stack;
+  const falsyCause2 = new Error(undefined, { cause: null });
+  falsyCause2.stack = '';
+
+  assert.strictEqual(util.inspect(falsyCause1), '[Error] { [cause]: false }');
+  assert.strictEqual(util.inspect(falsyCause2), '[Error] { [cause]: null }');
+}
+
 {
   const tmp = Error.stackTraceLimit;
   Error.stackTraceLimit = 0;