assert: support symbols as assertion messages

Currently, assertion messages are implicitly converted to strings,
which causes symbols to throw. This commit adds an explicit
string conversion.

PR-URL: #20693
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: cjihrig

lib/internal/assert.js

@@ -196,7 +196,7 @@ class AssertionError extends Error {
     } = options;
 
     if (message != null) {
-      super(message);
+      super(String(message));
     } else {
       if (process.stdout.isTTY) {
         // Reset on each call to make sure we handle dynamically set environment

test/parallel/test-assert.js

@@ -640,6 +640,16 @@ common.expectsError(
   }
 );
 
+common.expectsError(
+  () => assert(false, Symbol('foo')),
+  {
+    code: 'ERR_ASSERTION',
+    type: assert.AssertionError,
+    generatedMessage: false,
+    message: 'Symbol(foo)'
+  }
+);
+
 {
   // Test caching.
   const fs = process.binding('fs');