Fix undefined offset error

Author: przepompownia

src/BashCompletionPlugin.php

@@ -7,7 +7,6 @@
 use Composer\Plugin\PluginInterface;
 use Symfony\Component\Console\Application;
 use Symfony\Component\Console\Input\ArgvInput;
-use Symfony\Component\Console\Input\ArrayInput;
 
 class BashCompletionPlugin implements PluginInterface
 {
@@ -23,6 +22,10 @@ public function activate(Composer $composer, IOInterface $io)
         global $application;
         global $__bashCompletionInjected;
 
+        if (count($argv) < 2) {
+            return;
+        }
+
         // Inject completion command when the command line is `composer depends _completion`
         if ($argv[1] == 'depends' && $argv[2] == '_completion' && !$__bashCompletionInjected) {
             $__bashCompletionInjected = true;