Merge pull request #4401 from antograssiot/3.0

3.0 avoid fatal error by throwing exception

src/Utility/ObjectRegistry.php

@@ -72,7 +72,7 @@ abstract class ObjectRegistry {
 			$objectName = $config['className'];
 		}
 		$className = $this->_resolveClassName($objectName);
-		if (!$className) {
+		if (!$className || (is_string($className) && !class_exists($className))) {
 			list($plugin, $objectName) = pluginSplit($objectName);
 			$this->_throwMissingClassError($objectName, $plugin);
 		}

tests/TestCase/Datasource/ConnectionManagerTest.php

@@ -75,7 +75,7 @@ class ConnectionManagerTest extends TestCase {
  */
 	public function testConfigInvalidOptions() {
 		ConnectionManager::config('test_variant', [
-			'className' => 'HerpDerp'
+			'className' => 'Herp\Derp'
 		]);
 		ConnectionManager::get('test_variant');
 	}