Deprecate returning a non-integer value from a \Closure function set via Command::setCode()

Author: yceruto

Tests/Console/ApplicationTest.php

@@ -135,7 +135,11 @@ public function testRunOnlyWarnsOnUnregistrableCommand()
         $kernel
             ->method('getBundles')
             ->willReturn([$this->createBundleMock(
-                [(new Command('fine'))->setCode(function (InputInterface $input, OutputInterface $output) { $output->write('fine'); })]
+                [(new Command('fine'))->setCode(function (InputInterface $input, OutputInterface $output): int {
+                    $output->write('fine');
+
+                    return 0;
+                })]
             )]);
         $kernel
             ->method('getContainer')
@@ -163,7 +167,11 @@ public function testRegistrationErrorsAreDisplayedOnCommandNotFound()
         $kernel
             ->method('getBundles')
             ->willReturn([$this->createBundleMock(
-                [(new Command(null))->setCode(function (InputInterface $input, OutputInterface $output) { $output->write('fine'); })]
+                [(new Command(null))->setCode(function (InputInterface $input, OutputInterface $output): int {
+                    $output->write('fine');
+
+                    return 0;
+                })]
             )]);
         $kernel
             ->method('getContainer')
@@ -193,7 +201,11 @@ public function testRunOnlyWarnsOnUnregistrableCommandAtTheEnd()
         $kernel
             ->method('getBundles')
             ->willReturn([$this->createBundleMock(
-                [(new Command('fine'))->setCode(function (InputInterface $input, OutputInterface $output) { $output->write('fine'); })]
+                [(new Command('fine'))->setCode(function (InputInterface $input, OutputInterface $output): int {
+                    $output->write('fine');
+
+                    return 0;
+                })]
             )]);
         $kernel
             ->method('getContainer')