From c8a66b2e59461a57226cdb9440031278ffaef944 Mon Sep 17 00:00:00 2001
From: Sirz Benjie <142067137+SirzBenjie@users.noreply.github.com>
Date: Tue, 26 Aug 2025 01:48:55 -0500
Subject: [PATCH] [Bug] Prevent an empty starterpreferences object from being
 saved (#6410)

* Prevent an empty starterpreferences object from being saved

* Fix ssui nullish coalescing

* Update src/utils/data.ts

Co-authored-by: Dean <69436131+emdeann@users.noreply.github.com>

---------

Co-authored-by: Dean <69436131+emdeann@users.noreply.github.com>
---
 src/ui/starter-select-ui-handler.ts |  7 ++++---
 src/utils/data.ts                   | 23 ++++++++++++++++++++---
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/ui/starter-select-ui-handler.ts b/src/ui/starter-select-ui-handler.ts
index a29a65aca80..7396608bfc4 100644
--- a/src/ui/starter-select-ui-handler.ts
+++ b/src/ui/starter-select-ui-handler.ts
@@ -1828,9 +1828,9 @@ export class StarterSelectUiHandler extends MessageUiHandler {
       // The persistent starter data to apply e.g. candy upgrades
       const persistentStarterData = globalScene.gameData.starterData[this.lastSpecies.speciesId];
       // The sanitized starter preferences
-      let starterAttributes = this.starterPreferences[this.lastSpecies.speciesId];
+      let starterAttributes = this.starterPreferences[this.lastSpecies.speciesId] ?? {};
       // The original starter preferences
-      const originalStarterAttributes = this.originalStarterPreferences[this.lastSpecies.speciesId];
+      const originalStarterAttributes = this.originalStarterPreferences[this.lastSpecies.speciesId] ?? {};
 
       // this gets the correct pokemon cursor depending on whether you're in the starter screen or the party icons
       if (!this.starterIconsCursorObj.visible) {
@@ -3408,8 +3408,9 @@ export class StarterSelectUiHandler extends MessageUiHandler {
       if (species) {
         const defaultDexAttr = this.getCurrentDexProps(species.speciesId);
         const defaultProps = globalScene.gameData.getSpeciesDexAttrProps(species, defaultDexAttr);
+        // Bang is correct due to the `?` before variant
         const variant = this.starterPreferences[species.speciesId]?.variant
-          ? (this.starterPreferences[species.speciesId].variant as Variant)
+          ? (this.starterPreferences[species.speciesId]!.variant as Variant)
           : defaultProps.variant;
         const tint = getVariantTint(variant);
         this.pokemonShinyIcon.setFrame(getVariantIcon(variant)).setTint(tint);
diff --git a/src/utils/data.ts b/src/utils/data.ts
index 6580ecf2ee9..337aac1110b 100644
--- a/src/utils/data.ts
+++ b/src/utils/data.ts
@@ -64,7 +64,7 @@ const StarterPrefers_DEFAULT: string = "{}";
 let StarterPrefers_private_latest: string = StarterPrefers_DEFAULT;
 
 export interface StarterPreferences {
-  [key: number]: StarterAttributes;
+  [key: number]: StarterAttributes | undefined;
 }
 // called on starter selection show once
 
@@ -74,10 +74,27 @@ export function loadStarterPreferences(): StarterPreferences {
       localStorage.getItem(`starterPrefs_${loggedInUser?.username}`) || StarterPrefers_DEFAULT),
   );
 }
-// called on starter selection clear, always
+
+/**
+ * Check if an object has no properties of its own (its shape is `{}`)
+ * @param obj - Object to check
+ * @returns - Whether the object is bare
+ */
+export function isBareObject(obj: object): boolean {
+  for (const _ in obj) {
+    return false;
+  }
+  return true;
+}
 
 export function saveStarterPreferences(prefs: StarterPreferences): void {
-  const pStr: string = JSON.stringify(prefs);
+  // Fastest way to check if an object has any properties (does no allocation)
+  if (isBareObject(prefs)) {
+    console.warn("Refusing to save empty starter preferences");
+    return;
+  }
+  // no reason to store `{}` (for starters not customized)
+  const pStr: string = JSON.stringify(prefs, (_, value) => (isBareObject(value) ? undefined : value));
   if (pStr !== StarterPrefers_private_latest) {
     // something changed, store the update
     localStorage.setItem(`starterPrefs_${loggedInUser?.username}`, pStr);