Refactor exception handler to v3, use standard shell exitcode

src/StaticPHP/Command/Dev/EnvCommand.php

@@ -29,7 +29,7 @@ class EnvCommand extends BaseCommand
         $env = $this->getArgument('env');
         if (($val = getenv($env)) === false) {
             $this->output->writeln("<error>Environment variable '{$env}' is not set.</error>");
-            return static::FAILURE;
+            return static::USER_ERROR;
         }
         if (is_array($val)) {
             foreach ($val as $k => $v) {

src/StaticPHP/Command/Dev/IsInstalledCommand.php

@@ -29,6 +29,6 @@ class IsInstalledCommand extends BaseCommand
             return static::SUCCESS;
         }
         $this->output->writeln("<error>Package [{$package}] is not installed.</error>");
-        return static::FAILURE;
+        return static::USER_ERROR;
     }
 }

src/StaticPHP/Command/Dev/LintConfigCommand.php

@@ -34,7 +34,7 @@ class LintConfigCommand extends BaseCommand
 
         if ($checkOnly && $hasChanges) {
             $this->output->writeln('<error>Some config files need sorting. Run "bin/spc dev:lint-config" to fix them.</error>');
-            return static::FAILURE;
+            return static::VALIDATION_ERROR;
         }
 
         return static::SUCCESS;
@@ -125,7 +125,7 @@ class LintConfigCommand extends BaseCommand
             return false;
         }
         ksort($data);
-        foreach ($data as $artifact_name => &$config) {
+        foreach ($data as &$config) {
             uksort($config, $config_type === 'artifact' ? [$this, 'artifactSortKey'] : [$this, 'packageSortKey']);
         }
         unset($config);

src/StaticPHP/Command/Dev/ShellCommand.php

@@ -28,6 +28,6 @@ class ShellCommand extends BaseCommand
             return $code;
         }
         $this->output->writeln('<error>Unsupported OS for shell command.</error>');
-        return static::FAILURE;
+        return static::ENVIRONMENT_ERROR;
     }
 }