Compatibility with Composer 2.5.6

Author: ondrejmirtes

composer.json

@@ -8,7 +8,7 @@
     "require": {
         "php": "^7.2 || ^8.0",
         "composer-plugin-api": "^2.0",
-        "phpstan/phpstan": "^1.8.0"
+        "phpstan/phpstan": "^1.9.0"
     },
     "require-dev": {
         "composer/composer": "^2.0",

phpstan.neon

@@ -5,3 +5,9 @@ parameters:
 	level: 8
 	paths:
 		- src
+
+	ignoreErrors:
+		-
+			message: '#^Strict comparison using \=\=\= between string and null will always evaluate to false\.$#'
+			reportUnmatched: false
+			path: src/Plugin.php

src/Plugin.php

@@ -135,6 +135,9 @@ public function process(Event $event): void
 			}
 
 			$installPath = $installationManager->getInstallPath($package);
+			if ($installPath === null) {
+				continue;
+			}
 
 			$absoluteInstallPath = $fs->isAbsolutePath($installPath)
 				? $installPath