fix(optimizer): handle first-class callable placeholders in property optimizer

- Add check for Node\Arg instance before accessing arg properties
- Skip non-Node\Arg arguments that represent callable placeholders
- Prevent errors when processing first-class callables like $object->method(...)
- Ensure property optimizer correctly handles variadic placeholders
- Maintain existing refval function call detection logic
- Add test case for first-class callable property optimization scenario

src/Optimizer/SsaPropOptimizer.php

@@ -452,7 +452,8 @@ trait SsaPropOptimizer
         if ($node instanceof Expr\FuncCall
             && $node->name instanceof Node\Name
             && $node->name->toLowerString() === 'refval'
-            && !empty($node->args)) {
+            && isset($node->args[0])
+            && $node->args[0] instanceof Node\Arg) {
             $propName = $this->getPropNameOfObj($node->args[0]->value, $objName);
             if ($propName !== null) {
                 $events[] = ['kind' => 'danger', 'prop' => $propName];
@@ -476,6 +477,12 @@ trait SsaPropOptimizer
                 $this->collectPropEvents($node->var, $objName, $events);
             }
             foreach ($node->args as $arg) {
+                // A first-class callable such as $object->method(...) stores a
+                // VariadicPlaceholder in args. It denotes callable creation,
+                // not an argument expression, and has no byRef/value fields.
+                if (!$arg instanceof Node\Arg) {
+                    continue;
+                }
                 $propName = $arg->byRef ? $this->getPropNameOfObj($arg->value, $objName) : null;
                 if ($propName !== null) {
                     $events[] = ['kind' => 'danger', 'prop' => $propName];
@@ -490,6 +497,9 @@ trait SsaPropOptimizer
                     $events[] = ['kind' => 'danger', 'prop' => '*'];
                 }
                 foreach ($node->args as $arg) {
+                    if (!$arg instanceof Node\Arg) {
+                        continue;
+                    }
                     if ($this->exprMayExposeObject($arg->value, $objName)) {
                         $events[] = ['kind' => 'danger', 'prop' => '*'];
                     }

tests/compiler/callable/first-class-callable-property-optimizer.phpt

@@ -0,0 +1,32 @@
+--TEST--
+First-class callable placeholder is not treated as a call argument by property optimizer
+--FILE--
+<?php
+
+use native_types;
+
+class FirstClassCallableTarget
+{
+    public int $counter = 0;
+
+    public function tick(): void
+    {
+        $this->counter++;
+    }
+
+    public function invoke(callable $callback): void
+    {
+        $callback();
+    }
+}
+
+function main(): void
+{
+    $target = new FirstClassCallableTarget();
+    $target->invoke($target->tick(...));
+    var_dump($target->counter);
+}
+
+?>
+--EXPECT--
+int(1)