Truncate description of huge UnionType

Author: ondrejmirtes

src/Type/UnionType.php

@@ -29,6 +29,7 @@
 use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use function array_map;
 use function array_merge;
+use function array_slice;
 use function array_unique;
 use function array_values;
 use function count;
@@ -292,6 +293,10 @@ public function describe(VerbosityLevel $level): string
 				}
 			}
 
+			if (count($typeNames) > 1024) {
+				return implode('|', array_slice($typeNames, 0, 1024)) . "|\u{2026}";
+			}
+
 			return implode('|', $typeNames);
 		};