Throw exception when mapping non-flat values in flat typed properties

Flat types can all be casted to each other,
but objects and arrays can't be casted to flat types.

Previously an E_NOTICE has been raised:
> Array to string conversion

This is prevented now, and a proper JsonMapper_Exception is thrown.

src/JsonMapper.php

@@ -245,11 +245,11 @@ public function map($json, $object)
             } else if ($this->isSimpleType($type)
                 && !(is_array($jvalue) && $this->hasVariadicArrayType($accessor))
             ) {
-                if ($type === 'string' && is_object($jvalue)) {
+                if ($this->isFlatType($type) && !$this->isFlatType(gettype($jvalue))) {
                     throw new JsonMapper_Exception(
                         'JSON property "' . $key . '" in class "'
-                        . $strClassName . '" is an object and'
-                        . ' cannot be converted to a string'
+                        . $strClassName . '" is of type ' . gettype($jvalue) . ' and'
+                        . ' cannot be converted to ' . $type
                     );
                 }
                 settype($jvalue, $type);

tests/JsonMapperTest/ArrayValueForStringProperty.php

@@ -0,0 +1,16 @@
+<?php
+/**
+ * Part of JsonMapper
+ *
+ * PHP version 5
+ *
+ * @package  JsonMapper
+ * @author   Christian Weiske <[email protected]>
+ * @license  OSL-3.0 http://opensource.org/licenses/osl-3.0
+ * @link     http://cweiske.de/
+ */
+
+class JsonMapperTest_ArrayValueForStringProperty
+{
+	public string $value;
+}

tests/ObjectTest.php

@@ -194,7 +194,7 @@ public function testObjectInvalidNull()
     public function testObjectInsteadOfString()
     {
         $this->expectException(JsonMapper_Exception::class);
-        $this->expectExceptionMessage('JSON property "pString" in class "JsonMapperTest_Object" is an object and cannot be converted to a string');
+        $this->expectExceptionMessage('JSON property "pString" in class "JsonMapperTest_Object" is of type object and cannot be converted to string');
         $jm = new JsonMapper();
         $sn = $jm->map(
             json_decode('{"pString":{"key":"val"}}'),

tests/SimpleTest.php

@@ -247,5 +247,22 @@ public function testMapSimpleHyphenSetter()
         );
 
     }
+
+    /**
+     * @requires PHP 7.4
+     */
+    public function testMapArrayValueToStringProperty()
+    {
+        //do that here and not on top of the file - only for php 7.4+
+        require_once 'JsonMapperTest/ArrayValueForStringProperty.php';
+
+        $jm = new JsonMapper();
+        $this->expectException(JsonMapper_Exception::class);
+        $this->expectExceptionMessage('JSON property "value" in class "JsonMapperTest_ArrayValueForStringProperty" is of type array and cannot be converted to string');
+        $jm->map(
+            json_decode('{"value":[]}'),
+            new JsonMapperTest_ArrayValueForStringProperty()
+        );
+    }
 }
 ?>