util: gracefully handle unknown colors

This makes sure colors that are unknown won't cause an error. This
is especially important in case a library wants to use colors
defined by Node.js core, if available and fall back to the default
otherwise.

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

PR-URL: #33797
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

lib/internal/util/inspect.js

@@ -478,7 +478,8 @@ function stylizeWithColor(str, styleType) {
   const style = inspect.styles[styleType];
   if (style !== undefined) {
     const color = inspect.colors[style];
-    return `\u001b[${color[0]}m${str}\u001b[${color[1]}m`;
+    if (color !== undefined)
+      return `\u001b[${color[0]}m${str}\u001b[${color[1]}m`;
   }
   return str;
 }

test/parallel/test-util-inspect.js

@@ -2245,6 +2245,12 @@ assert.strictEqual(
     assert.deepStrictEqual(inspect.colors[bgColor], [40 + i, 49]);
     assert.deepStrictEqual(inspect.colors[`${bgColor}Bright`], [100 + i, 49]);
   });
+
+  // Unknown colors are handled gracefully:
+  const stringStyle = inspect.styles.string;
+  inspect.styles.string = 'UNKNOWN';
+  assert.strictEqual(inspect('foobar', { colors: true }), "'foobar'");
+  inspect.styles.string = stringStyle;
 }
 
 assert.strictEqual(