Simplify reproduction command (#2797)

diff --git a/lib/src/command.dart b/lib/src/command.dart
index 37f1335..b6eaab1 100644
--- a/lib/src/command.dart
+++ b/lib/src/command.dart
@@ -183,7 +183,7 @@
         log.error("""
 This is an unexpected error. Please run
 
-    pub --trace ${runner.executableName} ${_topCommand.name} ${_topCommand.argResults.arguments.map(protectArgument).join(' ')}
+    dart pub --trace ${_topCommand.name} ${_topCommand.argResults.arguments.map(protectArgument).join(' ')}
 
 and include the logs in an issue on https://github.com/dart-lang/pub/issues/new
 """);