Handle incorrect usage of subscribe in stores

If the unsubscribe function is called multiple times the indexOf
function will return -1 which will end up removing random other
subscription callbacks.  Prevent the incorrect callabck removial
in this case.

packages/web_ui/src/store/default_mod_pack_store.ts

@@ -35,7 +35,10 @@ class DefaultModPackStore {
 		this.callbacks.push(callback);
 		this.refCount += 1;
 		return () => {
-			this.callbacks.splice(this.callbacks.indexOf(callback), 1);
+			const index = this.callbacks.indexOf(callback);
+			if (index !== -1) {
+				this.callbacks.splice(index, 1);
+			}
 			this.refCount -= 1;
 			if (this.refCount === 0) {
 				clearInterval(this.interval);

packages/web_ui/src/store/export_locale_stores.ts

@@ -47,7 +47,10 @@ class ExportLocaleStore {
 		}
 		cacheEntry.callbacks.push(callback);
 		return () => {
-			cacheEntry.callbacks.splice(cacheEntry.callbacks.indexOf(callback), 1);
+			const index = cacheEntry.callbacks.indexOf(callback);
+			if (index !== -1) {
+				cacheEntry.callbacks.splice(index, 1);
+			}
 		};
 	}
 

packages/web_ui/src/store/export_prototype_metadata_store.ts

@@ -112,7 +112,10 @@ class ExportPrototypeMetadataStore {
 		}
 		cacheEntry.callbacks.push(callback);
 		return () => {
-			cacheEntry.callbacks.splice(cacheEntry.callbacks.indexOf(callback), 1);
+			const index = cacheEntry.callbacks.indexOf(callback);
+			if (index !== -1) {
+				cacheEntry.callbacks.splice(index, 1);
+			}
 		};
 	}