Issue 35901: explode(): Argument #2 () must be of type string, null g…

app/code/Magento/Catalog/view/adminhtml/templates/catalog/product/edit/action/inventory.phtml

@@ -94,7 +94,7 @@ if (!is_numeric($defaultMinSaleQty)) {
                     <div class="field">
                         <input type="text" class="input-text required-entry validate-number" id="inventory_qty"
                                name="<?= /* @noEscape */ $block->getFieldSuffix() ?>[qty]"
-                               value="<?= $block->getDefaultConfigValue('qty') * 1 ?>" disabled="disabled"/>
+                               value="<?= (float) $block->getDefaultConfigValue('qty') * 1 ?>" disabled="disabled"/>
                     </div>
                     <div class="field choice">
                         <input type="checkbox" id="inventory_qty_checkbox" data-role="toggle-editability-all"/>
@@ -116,7 +116,7 @@ if (!is_numeric($defaultMinSaleQty)) {
                     <div class="field">
                         <input type="text" class="input-text validate-number" id="inventory_min_qty"
                                name="<?= /* @noEscape */ $block->getFieldSuffix() ?>[min_qty]"
-                               value="<?= $block->getDefaultConfigValue('min_qty') * 1 ?>" disabled="disabled"/>
+                               value="<?= (float) $block->getDefaultConfigValue('min_qty') * 1 ?>" disabled="disabled"/>
                     </div>
                     <div class="field choice">
                         <input type="checkbox" id="inventory_use_config_min_qty"
@@ -179,7 +179,7 @@ if (!is_numeric($defaultMinSaleQty)) {
                     <div class="field">
                         <input type="text" class="input-text validate-number" id="inventory_max_sale_qty"
                                name="<?= /* @noEscape */ $block->getFieldSuffix() ?>[max_sale_qty]"
-                               value="<?= $block->getDefaultConfigValue('max_sale_qty') * 1 ?>"
+                               value="<?= (float) $block->getDefaultConfigValue('max_sale_qty') * 1 ?>"
                                disabled="disabled"/>
                     </div>
                     <div class="field choice">
@@ -287,7 +287,7 @@ if (!is_numeric($defaultMinSaleQty)) {
                     <div class="field">
                         <input type="text" class="input-text validate-number" id="inventory_notify_stock_qty"
                                name="<?= /* @noEscape */ $block->getFieldSuffix() ?>[notify_stock_qty]"
-                               value="<?= $block->getDefaultConfigValue('notify_stock_qty') * 1 ?>"
+                               value="<?= (float) $block->getDefaultConfigValue('notify_stock_qty') * 1 ?>"
                                disabled="disabled"/>
                     </div>
                     <div class="field choice">
@@ -364,7 +364,7 @@ if (!is_numeric($defaultMinSaleQty)) {
                     <div class="field">
                         <input type="text" class="input-text validate-number" id="inventory_qty_increments"
                                name="<?= /* @noEscape */ $block->getFieldSuffix() ?>[qty_increments]"
-                               value="<?= $block->getDefaultConfigValue('qty_increments') * 1 ?>"
+                               value="<?= (float) $block->getDefaultConfigValue('qty_increments') * 1 ?>"
                                disabled="disabled"/>
                     </div>
                     <div class="field choice">

lib/internal/Magento/Framework/App/Config.php

@@ -1,7 +1,5 @@
 <?php
 /**
- * Application configuration object. Used to access configuration when application is initialized and installed.
- *
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
@@ -12,14 +10,14 @@
 use Magento\Framework\App\Config\ScopeConfigInterface;
 
 /**
- * Class Config
+ * Application configuration object. Used to access configuration when application is initialized and installed.
  */
 class Config implements ScopeConfigInterface
 {
     /**
      * Config cache tag
      */
-    const CACHE_TAG = 'CONFIG';
+    public const CACHE_TAG = 'CONFIG';
 
     /**
      * @var ScopeCodeResolver
@@ -132,6 +130,6 @@ public function get($configType, $path = '', $default = null)
             $result = $this->types[$configType]->get($path);
         }
 
-        return $result !== null ? $result : $default;
+        return $result ?? $default ?? '';
     }
 }

lib/internal/Magento/Framework/App/Test/Unit/ConfigTest.php

@@ -14,6 +14,9 @@
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 
+/**
+ * Application configuration test
+ */
 class ConfigTest extends TestCase
 {
     /**
@@ -36,6 +39,9 @@ class ConfigTest extends TestCase
      */
     private $appConfig;
 
+    /**
+     * @return void
+     */
     protected function setUp(): void
     {
         $this->scopeCodeResolver = $this->getMockBuilder(ScopeCodeResolver::class)
@@ -77,6 +83,21 @@ public function testGetValue($scope, $scopeCode = null)
         $this->assertTrue($this->appConfig->getValue($path, $scope, $scopeCode ?: $this->scope));
     }
 
+    /**
+     * @param $default
+     * @param $result
+     * @dataProvider getDataProvider
+     * @return void
+     */
+    public function testGet($default, $result)
+    {
+        $path = 'path';
+        $this->configType->expects($this->any())
+            ->method('get')
+            ->willReturn($default);
+        $this->assertSame($result, $this->appConfig->get('system', $path, $default));
+    }
+
     /**
      * @return array
      */
@@ -87,4 +108,16 @@ public function getValueDataProvider()
             ['website'],
         ];
     }
+
+    /**
+     * @return array
+     */
+    public function getDataProvider()
+    {
+        return [
+            [1, 1],
+            [[1,2,3], [1,2,3]],
+            [null, ''],
+        ];
+    }
 }