[jnigen] colorized warning in logger (https://github.com/dart-lang/jnigen/issues/107)

pkgs/jnigen/lib/src/logging/logging.dart

diff --git a/pkgs/jnigen/lib/src/logging/logging.dart b/pkgs/jnigen/lib/src/logging/logging.dart
index db8b713..bf4bbe9 100644
--- a/pkgs/jnigen/lib/src/logging/logging.dart
+++ b/pkgs/jnigen/lib/src/logging/logging.dart
@@ -6,31 +6,42 @@
 import 'package:logging/logging.dart';
 
 const _ansiRed = '\x1b[31m';
+const _ansiYellow = '\x1b[33m';
 const _ansiDefault = '\x1b[39;49m';
 
+String _colorize(String message, String colorCode) {
+  if (stderr.supportsAnsiEscapes) {
+    return '$colorCode$message$_ansiDefault';
+  }
+  return message;
+}
+
 Logger log = Logger('jnigen');
 
+/// Set logging level to [level] and initialize the logger.
 void setLoggingLevel(Level level) {
   Logger.root.level = level;
   Logger.root.onRecord.listen((r) {
     var message = '(${r.loggerName}) ${r.level.name}: ${r.message}';
-    if (level == Level.SHOUT || level == Level.SEVERE) {
-      message = '$_ansiRed$message$_ansiDefault';
+    if ((r.level == Level.SHOUT || r.level == Level.SEVERE)) {
+      message = _colorize(message, _ansiRed);
+    } else if (r.level == Level.WARNING) {
+      message = _colorize(message, _ansiYellow);
     }
     stderr.writeln(message);
   });
 }
 
+/// Prints [message] without logging information.
+///
+/// Primarily used in printing output of failed commands.
 void printError(Object? message) {
-  if (stderr.supportsAnsiEscapes) {
-    message = '$_ansiRed$message$_ansiDefault';
-  }
-  stderr.writeln(message);
+  stderr.writeln(_colorize(message.toString(), _ansiRed));
 }
 
 extension FatalErrors on Logger {
   void fatal(Object? message, {int exitCode = 2}) {
-    message = '${_ansiRed}Fatal: $message$_ansiDefault';
+    message = _colorize('Fatal: $message', _ansiRed);
     stderr.writeln(message);
     exit(exitCode);
   }