simplify

packages/svelte/src/internal/client/runtime.js

@@ -248,16 +248,14 @@ export function check_dirtiness(reaction) {
 						is_dirty = true;
 					}
 					reactions = dependency.reactions;
-					if (reactions === null || !reactions.includes(reaction)) {
 					if (reactions === null) {
 						dependency.reactions = [reaction];
-						} else {
+					} else if (!reactions.includes(reaction)) {
 						reactions.push(reaction);
 					}
 				}
 			}
 		}
-		}
 
 		// Unowned signals are always maybe dirty, as we instead check their dependency versions.
 		if (!is_unowned) {