diff --git a/core/src/subscriber/watcher.ts b/core/src/subscriber/watcher.ts
index 9864804a..a83c74dc 100644
--- a/core/src/subscriber/watcher.ts
+++ b/core/src/subscriber/watcher.ts
@@ -101,18 +101,16 @@ export class AddressWatcher {
         if (assetId) {
             const assetKey = `${key} ${assetId}`;
             return new Promise<Trade[]>((resolve, reject) => {
-                if (!this.assetIdResolvers.has(assetKey)) {
-                    this.assetIdResolvers.set(assetKey, []);
-                }
-                this.assetIdResolvers.get(assetKey)!.push({ resolve, reject });
+                const list = this.assetIdResolvers.get(assetKey) ?? [];
+                list.push({ resolve, reject });
+                this.assetIdResolvers.set(assetKey, list);
             });
         }
 
         return new Promise<SubscribedAddressSnapshot>((resolve, reject) => {
-            if (!this.resolvers.has(key)) {
-                this.resolvers.set(key, []);
-            }
-            this.resolvers.get(key)!.push({ resolve, reject });
+            const list = this.resolvers.get(key) ?? [];
+            list.push({ resolve, reject });
+            this.resolvers.set(key, list);
         });
     }
 
diff --git a/core/src/utils/market-utils.ts b/core/src/utils/market-utils.ts
index c54e431e..c3131a7b 100644
--- a/core/src/utils/market-utils.ts
+++ b/core/src/utils/market-utils.ts
@@ -46,11 +46,11 @@ export function addBinaryOutcomes(market: UnifiedMarket): void {
     // those are meaningful labels for financial markets.
     const yesLabel = market.yes?.label.toLowerCase();
     const noLabel = market.no?.label.toLowerCase();
-    if (market.title && yesLabel === 'yes') {
-        market.yes!.label = market.title;
+    if (market.title && market.yes && yesLabel === 'yes') {
+        market.yes = { ...market.yes, label: market.title };
     }
-    if (market.title && noLabel === 'no') {
-        market.no!.label = `Not ${market.title}`;
+    if (market.title && market.no && noLabel === 'no') {
+        market.no = { ...market.no, label: `Not ${market.title}` };
     }
 
     market.up = market.yes;
diff --git a/core/src/utils/throttler.ts b/core/src/utils/throttler.ts
index 4b299dd3..7673f5e1 100644
--- a/core/src/utils/throttler.ts
+++ b/core/src/utils/throttler.ts
@@ -7,19 +7,28 @@ export class Throttler {
     private refillRate: number;
     private capacity: number;
     private delay: number;
+    private maxQueueDepth: number;
 
     constructor(config: {
         refillRate: number;   // tokens per ms (1 / rateLimit)
         capacity: number;     // max tokens
         delay: number;        // polling interval in ms
+        maxQueueDepth?: number; // max queued requests (default 1000)
     }) {
         this.refillRate = config.refillRate;
         this.capacity = config.capacity;
         this.delay = config.delay;
+        this.maxQueueDepth = config.maxQueueDepth ?? 1000;
     }
 
     async throttle(cost: number = 1): Promise<void> {
         return new Promise<void>((resolve) => {
+            if (this.queue.length >= this.maxQueueDepth) {
+                const dropped = this.queue.shift();
+                if (dropped) {
+                    dropped.resolve();
+                }
+            }
             this.queue.push({ resolve, cost });
             if (!this.running) {
                 this.running = true;