ENGCOM-7961: Fix for #29315: \Magento\Config\Model\Config\Source\Email\Tem… #29316

 - Merge Pull Request #29316 from willwright/magento2:issue-29315
 - Merged commits:
   1. e786d51
   2. e0972bf

Author: magento-engcom-team

app/code/Magento/Config/Model/Config/Source/Email/Template.php

@@ -60,10 +60,12 @@ public function toOptionArray()
             $this->_coreRegistry->register('config_system_email_template', $collection);
         }
         $options = $collection->toOptionArray();
-        $templateId = str_replace('/', '_', $this->getPath());
-        $templateLabel = $this->_emailConfig->getTemplateLabel($templateId);
-        $templateLabel = __('%1 (Default)', $templateLabel);
-        array_unshift($options, ['value' => $templateId, 'label' => $templateLabel]);
+        if (!empty($this->getPath())) {
+            $templateId = str_replace('/', '_', $this->getPath());
+            $templateLabel = $this->_emailConfig->getTemplateLabel($templateId);
+            $templateLabel = __('%1 (Default)', $templateLabel);
+            array_unshift($options, ['value' => $templateId, 'label' => $templateLabel]);
+        }
         return $options;
     }
 }

app/code/Magento/Config/Test/Unit/Model/Config/Source/Email/TemplateTest.php

@@ -102,4 +102,53 @@ public function testToOptionArray()
         $this->_model->setPath('template/new');
         $this->assertEquals($expectedResult, $this->_model->toOptionArray());
     }
+
+    public function testToOptionArrayWithoutPath()
+    {
+        $collection = $this->createMock(Collection::class);
+        $collection->expects(
+            $this->once()
+        )->method(
+            'toOptionArray'
+        )->willReturn(
+            [
+                ['value' => 'template_one', 'label' => 'Template One'],
+                ['value' => 'template_two', 'label' => 'Template Two'],
+            ]
+        );
+
+        $this->_coreRegistry->expects(
+            $this->once()
+        )->method(
+            'registry'
+        )->with(
+            'config_system_email_template'
+        )->willReturn(
+            $collection
+        );
+
+        $this->_emailConfig->expects(
+            $this->never()
+        )->method(
+            'getTemplateLabel'
+        )->with(
+            ''
+        )
+        ->willThrowException(
+            new \UnexpectedValueException("Email template '' is not defined.")
+        );
+
+        $expectedResult = [
+            [
+                'value' => 'template_one',
+                'label' => 'Template One',
+            ],
+            [
+                'value' => 'template_two',
+                'label' => 'Template Two',
+            ],
+        ];
+
+        $this->assertEquals($expectedResult, $this->_model->toOptionArray());
+    }
 }