Fix problems reported by PHPStan

src/ConditionsScript.php

@@ -7,7 +7,7 @@ trait ConditionsScript
     /**
      * If this Preloader should run
      *
-     * @var callable
+     * @var callable|null
      */
     protected $condition;
 

src/Opcache.php

@@ -27,7 +27,7 @@ class Opcache
      */
     public function getStatus() : array
     {
-        if ($this->status ??= opcache_get_status(true)) {
+        if ($this->status = $this->status ?: opcache_get_status(true)) {
             return $this->status;
         }
 

src/Preloader.php

@@ -135,7 +135,7 @@ protected function canGenerate(string $path, bool $overwrite) : bool
         }
 
         // If there is a condition, call it.
-        if ($this->condition) {
+        if (is_callable($this->condition)) {
             return (bool) call_user_func($this->condition);
         }
 
@@ -146,17 +146,17 @@ protected function canGenerate(string $path, bool $overwrite) : bool
      * Writes the preloader script file into the specified path.
      *
      * @param  string  $path
-     * @return false|int
+     * @return true
      *
      * @codeCoverageIgnore
      */
     protected function performWrite(string $path)
     {
-        if (file_put_contents($path, $this->prepareCompiler($path)->compile(), LOCK_EX)) {
-            return true;
+        if (file_put_contents($path, $this->prepareCompiler($path)->compile(), LOCK_EX) === false) {
+            throw new RuntimeException("Preloader couldn't write the script to [$path].");
         }
 
-        throw new RuntimeException("Preloader couldn't write the script to [$path].");
+        return true;
     }
 
     /**

src/PreloaderCompiler.php

@@ -11,7 +11,7 @@ class PreloaderCompiler
      *
      * @var false|string
      */
-    public string $contents;
+    public $contents;
 
     /**
      * Configuration array.
@@ -67,7 +67,7 @@ class PreloaderCompiler
      *
      * @return string|string[]
      */
-    public function compile() : string
+    public function compile()
     {
         $replacing = array_merge($this->preloaderConfig, $this->opcacheConfig, [
             '@output'       => $this->scriptRealPath(),
@@ -80,7 +80,7 @@ public function compile() : string
                 ? 'require_once $file' : 'opcache_compile_file($file)',
         ]);
 
-        return str_replace(array_keys($replacing), $replacing, $this->contents);
+        return str_replace(array_keys($replacing), $replacing, $this->contents ?: []);
     }
 
     /**