Return 0 in console commands

Per symfony/symfony#33747, required for
Symfony 5.0 upgrade.

src/php/Command/DumpCombinedEnvConfigCommand.php

@@ -25,7 +25,7 @@ protected function configure()
         $this->addArgument('env', InputArgument::REQUIRED, 'Name of the environment, e.g. “prod”, “stag”');
     }
 
-    public function execute(InputInterface $input, OutputInterface $output)
+    public function execute(InputInterface $input, OutputInterface $output): int
     {
         $path = dirname(__DIR__) . '/../../.env';
         $env = $input->getArgument('env');
@@ -39,6 +39,8 @@ public function execute(InputInterface $input, OutputInterface $output)
 EOF;
 
         file_put_contents($path . '.local.php', $vars, LOCK_EX);
+
+        return 0;
     }
 
     private function loadEnvVars(string $path, string $env): array

src/php/Command/GenerateVhostsCommand.php

@@ -69,11 +69,11 @@ protected function configure()
         );
     }
 
-    public function execute(InputInterface $input, OutputInterface $output)
+    public function execute(InputInterface $input, OutputInterface $output): int
     {
         $outputDir = $input->getArgument('path-to-vhosts');
         if (!is_string($outputDir)) {
-            return null;
+            return 0;
         }
         $repositoryRoot = realpath(__DIR__ . '/../../../');
 
@@ -100,5 +100,7 @@ public function execute(InputInterface $input, OutputInterface $output)
         $output->writeln('ALL DONE!');
         $output->writeln('✅ Vhosts generated and placed in ' . realpath($outputDir));
         $output->writeln('🐘 Don’t forget to reload nginx!');
+
+        return 0;
     }
 }