Remove getCode usage as it is not type safe apparently, see https://github.com/phpstan/phpstan-src/pull/795

src/Composer/DependencyResolver/SolverProblemsException.php

@@ -39,6 +39,14 @@ class SolverProblemsException extends \RuntimeException
         parent::__construct('Failed resolving dependencies with '.count($problems).' problems, call getPrettyString to get formatted details', self::ERROR_DEPENDENCY_RESOLUTION_FAILED);
     }
 
+    /**
+     * @return self::ERROR_DEPENDENCY_RESOLUTION_FAILED
+     */
+    public function getExitCode()
+    {
+        return self::ERROR_DEPENDENCY_RESOLUTION_FAILED;
+    }
+
     /**
      * @param bool $isVerbose
      * @param bool $isDevExtraction

src/Composer/Installer.php

@@ -455,7 +455,7 @@ class Installer
             $ghe = new GithubActionError($this->io);
             $ghe->emit($err."\n".$prettyProblem);
 
-            return max(self::ERROR_GENERIC_FAILURE, $e->getCode());
+            return max(self::ERROR_GENERIC_FAILURE, $e->getExitCode());
         }
 
         $this->io->writeError("Analyzed ".count($pool)." packages to resolve dependencies", true, IOInterface::VERBOSE);
@@ -633,7 +633,7 @@ class Installer
             $ghe = new GithubActionError($this->io);
             $ghe->emit($err."\n".$prettyProblem);
 
-            return max(self::ERROR_GENERIC_FAILURE, $e->getCode());
+            return max(self::ERROR_GENERIC_FAILURE, $e->getExitCode());
         }
 
         $lockTransaction->setNonDevPackages($nonDevLockTransaction);
@@ -703,7 +703,7 @@ class Installer
                 $ghe = new GithubActionError($this->io);
                 $ghe->emit($err."\n".$prettyProblem);
 
-                return max(self::ERROR_GENERIC_FAILURE, $e->getCode());
+                return max(self::ERROR_GENERIC_FAILURE, $e->getExitCode());
             }
         }