symfony
diff --git a/‎src/Symfony/Component/Console/Command/DumpCompletionCommand.php
Copy file name to clipboardExpand all lines: src/Symfony/Component/Console/Command/DumpCompletionCommand.php
+8-2Lines changed: 8 additions & 2 deletions b/‎src/Symfony/Component/Console/Command/DumpCompletionCommand.php
Copy file name to clipboardExpand all lines: src/Symfony/Component/Console/Command/DumpCompletionCommand.php
+8-2Lines changed: 8 additions & 2 deletions
@@ -93,8 +93,14 @@ protected function execute(InputInterface $input, OutputInterface $output): int
         if (!file_exists($completionFile)) {
             $supportedShells = $this->getSupportedShells();
 
-            ($output instanceof ConsoleOutputInterface ? $output->getErrorOutput() : $output)
-                ->writeln(sprintf('<error>Detected shell "%s", which is not supported by Symfony shell completion (supported shells: "%s").</>', $shell, implode('", "', $supportedShells)));
+            if ($output instanceof ConsoleOutputInterface) {
+                $output = $output->getErrorOutput();
+            }
+            if ($shell) {
+                $output->writeln(sprintf('<error>Detected shell "%s", which is not supported by Symfony shell completion (supported shells: "%s").</>', $shell, implode('", "', $supportedShells)));
+            } else {
+                $output->writeln(sprintf('<error>Shell not detected, Symfony shell completion only supports "%s").</>', implode('", "', $supportedShells)));
+            }
 
             return self::INVALID;
         }