Array in variables in place of object shouldn't cause fatal error (fixes #467)

src/Utils/Value.php

@@ -199,7 +199,7 @@ class Value
                 }
 
                 $suggestions = Utils::suggestionList(
-                    $fieldName,
+                    (string) $fieldName,
                     array_keys($fields)
                 );
                 $didYouMean  = $suggestions

tests/Regression/Issue467Test.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace GraphQL\Tests\Regression;
+
+use GraphQL\GraphQL;
+use GraphQL\Utils\BuildSchema;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @see https://github.com/webonyx/graphql-php/issues/467
+ */
+class Issue467Test extends TestCase
+{
+    public function testInputObjectValidation()
+    {
+        $schemaStr = '
+input MsgInput {
+  msg: String
+}
+
+type Query {
+  echo(msg: MsgInput): String
+}
+
+schema {
+    query: Query
+}
+';
+
+        $query     = '
+query echo ($msg: MsgInput) {
+          echo (msg: $msg)
+}';
+        $variables = ['msg' => ['my message']];
+
+        $schema = BuildSchema::build($schemaStr);
+        $result = GraphQL::executeQuery($schema, $query, null, null, $variables);
+
+        $expectedError = 'Variable "$msg" got invalid value ["my message"]; Field "0" is not defined by type MsgInput.';
+        self::assertCount(1, $result->errors);
+        self::assertEquals($expectedError, $result->errors[0]->getMessage());
+    }
+}