Replace RuntimeException with assert check in CompileVisitor

Replaced is_object check with an assert to test validity of instance type in CompileVisitor.php. Removed the usage of RuntimeException. Function "gettype" has been introduced for instance type identification. This refactoring lends to a cleaner code structure and exception handling.

src/CompileVisitor.php

@@ -13,9 +13,9 @@
 use Ray\Di\SetterMethods;
 use Ray\Di\VisitorInterface;
 use ReflectionParameter;
-use RuntimeException;
 
 use function assert;
+use function gettype;
 use function is_array;
 use function is_object;
 use function is_scalar;
@@ -70,11 +70,9 @@ public function visitInstance($value): string
             return 'return null;';
         }
 
-        if (is_object($value)) {
-            return sprintf('return unserialize(\'%s\');', serialize($value));
-        }
+        assert(! is_object($value), 'Invalid instance type:' . gettype($value));
 
-        throw new RuntimeException('Invalid instance value');
+        return sprintf('return unserialize(\'%s\');', serialize($value));
     }
 
     /** @inheritDoc */