Fix require command crashing at the end if no lock file is present, fixes #11814

src/Composer/Command/RequireCommand.php

@@ -558,6 +558,7 @@ EOT
                     throw new \RuntimeException('Unable to read '.$this->json->getPath().' contents to update the lock file hash.');
                 }
                 $lockFile = Factory::getLockFile($this->json->getPath());
+                if (file_exists($lockFile)) {
                     $lockMtime = filemtime($lockFile);
                     $lock = new JsonFile($lockFile);
                     $lockData = $lock->read();
@@ -568,6 +569,7 @@ EOT
                     }
                 }
             }
+        }
 
         return 0;
     }