feat: Add TomlParserNotFound exception

Author: roxblnfk

src/Common/EnvConfig/Client/ConfigToml.php

@@ -5,6 +5,7 @@
 namespace Temporal\Common\EnvConfig\Client;
 
 use Internal\Toml\Toml;
+use Temporal\Common\EnvConfig\Exception\TomlParserNotFoundException;
 
 /**
  * TOML configuration parser for Temporal client profiles.
@@ -57,6 +58,7 @@ public function __construct(
         string $toml,
         private readonly bool $strict = true,
     ) {
+        \class_exists(Toml::class) or throw new TomlParserNotFoundException();
         $data = Toml::parseToArray($toml);
         $this->profiles = $this->parseProfiles($data['profile'] ?? []);
     }

src/Common/EnvConfig/Exception/TomlParserNotFoundException.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Temporal\Common\EnvConfig\Exception;
+
+/**
+ * Thrown when the TOML parser package is not found.
+ */
+final class TomlParserNotFoundException extends ConfigException
+{
+    public function __construct()
+    {
+        parent::__construct(
+            'The package for parsing TOML files "internal/toml" is not found. ' .
+            'Please install it via Composer: `composer require internal/toml`.',
+        );
+    }
+}