fix(php): 修复变量重新赋值检查和unset操作的错误处理

- 修复数组类型变量重新赋值检查逻辑，排除VAR类型
- 优化错误消息格式，移除多余的空格
- 为unset操作添加未定义变量检查
- 为unset操作添加不支持类型的操作数错误处理
- 添加未定义变量测试用例
- 添加不支持的unset类型测试用例

phpunit/code/undefined-vars-01.php

@@ -0,0 +1,5 @@
+<?php
+function main()
+{
+    unset($u1, $u2);
+}

phpunit/code/unset-01.php

@@ -0,0 +1,5 @@
+<?php
+function main()
+{
+    unset(var_dump('1'));
+}

phpunit/src/UndefineTest.php

@@ -0,0 +1,10 @@
+<?php
+
+class UndefineTest extends \BaseTest
+{
+    public function testUnset()
+    {
+        $this->exec('The variable `$u1` is undefined', 'undefined-vars-01.php');
+        $this->exec('Unsupported unset type `Expr_FuncCall`', 'unset-01.php');
+    }
+}

src/Php/CompilerBase.php

@@ -1392,9 +1392,9 @@ class CompilerBase extends \PhpAot\Core\Translator
                 $this->addLocalVar($var, $type);
             } else {
                 if ($this->isTypedObject($var) and $type !== self::TYPE_OBJECT or
-                    $this->getVarType($var) === self::TYPE_ARRAY and $type !== self::TYPE_ARRAY
+                    $this->getVarType($var) === self::TYPE_ARRAY and ($type !== self::TYPE_ARRAY && $type !== self::TYPE_VAR)
                 ) {
-                    $this->fatalError($left, "Cannot re-assign variable `\${$var}` from " . $this->getVarType($var) . " to  " . $type);
+                    $this->fatalError($left, "Cannot re-assign variable `\${$var}` from " . $this->getVarType($var) . " to " . $type);
                 }
             }
         } elseif ($this->isPropertyFetch($left) and !$left->getAttribute('nativeProperty')) {
@@ -3191,9 +3191,12 @@ class CompilerBase extends \PhpAot\Core\Translator
                 $lines[] = $object . '.unsetProperty(' . $propName . ');';
             } elseif ($type === self::EXPR_VARIABLE) {
                 $name = $this->parseIdentifier($var);
+                if (!$this->hasVar($name)) {
+                    $this->errorUndefinedVariable($var);
+                }
                 $lines[] = "{$name}.unset();";
             } else {
-                abort($var);
+                $this->fatalError($var, "Unsupported unset type `{$type}`");
             }
         }