Actually include the ErrorTextHelper code

Author: Wout Gevaert

src/ErrorHandling/ErrorTextHelper.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace WikibaseSolutions\CypherDSL\ErrorHandling;
+
+class ErrorTextHelper {
+    public static function getTypeErrorObjectArrayText(
+        string $varName,
+        $typeNames,
+        $userInput
+    ) {
+        $userInputInfo = self::getUserInputInfo($userInput);
+
+        if (is_array($typeNames)) {
+            $typeNames = implode( ' or ', $typeNames );
+        }
+
+        return "\$$varName should consist of only $typeNames objects, $userInputInfo given.";
+    }
+
+    public static function getUserInputInfo($userInput) : string {
+        $info = gettype( $userInput );
+        if ( $info === 'object' ) {
+            $info = get_class( $userInput );
+        } else {
+            $givenType .= ' "' . (string) $userInput . '"';
+        }
+    }
+}