Use is_file() instead of file_exists() where possible

Author: nicolas-grekas

EnvVarProcessor.php

@@ -114,7 +114,7 @@ public function getEnv(string $prefix, string $name, \Closure $getEnv)
             if (!is_scalar($file = $getEnv($name))) {
                 throw new RuntimeException(sprintf('Invalid file name: env var "%s" is non-scalar.', $name));
             }
-            if (!file_exists($file)) {
+            if (!is_file($file)) {
                 throw new EnvNotFoundException(sprintf('File "%s" not found (resolved from "%s").', $file, $name));
             }
 

Loader/YamlFileLoader.php

@@ -670,7 +670,7 @@ protected function loadFile($file)
             throw new InvalidArgumentException(sprintf('This is not a local file "%s".', $file));
         }
 
-        if (!file_exists($file)) {
+        if (!is_file($file)) {
             throw new InvalidArgumentException(sprintf('The file "%s" does not exist.', $file));
         }