fix: resolve duplicate key and null message errors in chat (#20268)

* fix: resolve duplicate key and null message errors in chat

* fix: resolve duplicate key and null message errors in chat

* chore: visitedIds -> visitedMessageIds

src/lib/components/chat/Chat.svelte

@@ -1103,7 +1103,7 @@
 
 				if (history.currentId) {
 					for (const message of Object.values(history.messages)) {
-						if (message.role === 'assistant') {
+						if (message && message.role === 'assistant') {
 							message.done = true;
 						}
 					}
@@ -2084,8 +2084,10 @@
 
 			const responseMessage = history.messages[history.currentId];
 			// Set all response messages to done
-			for (const messageId of history.messages[responseMessage.parentId].childrenIds) {
+			if (responseMessage.parentId && history.messages[responseMessage.parentId]) {
-				history.messages[messageId].done = true;
+				for (const messageId of history.messages[responseMessage.parentId].childrenIds) {
+					history.messages[messageId].done = true;
+				}
 			}
 
 			history.messages[history.currentId] = responseMessage;

src/lib/components/chat/Messages.svelte

@@ -77,7 +77,15 @@
 		let _messages = [];
 
 		let message = history.messages[history.currentId];
+		const visitedMessageIds = new Set();
+
 		while (message && (messagesCount !== null ? _messages.length <= messagesCount : true)) {
+			if (visitedMessageIds.has(message.id)) {
+				console.warn('Circular dependency detected in message history', message.id);
+				break;
+			}
+			visitedMessageIds.add(message.id);
+
 			_messages.unshift({ ...message });
 			message = message.parentId !== null ? history.messages[message.parentId] : null;
 		}

src/lib/components/chat/Overview/View.svelte

@@ -75,6 +75,8 @@
 
 		Object.keys(history.messages).forEach((id) => {
 			const message = history.messages[id];
+			if (!message) return;
+
 			const level = message.parentId ? (positionMap.get(message.parentId)?.level ?? -1) + 1 : 0;
 			if (!layerWidths[level]) layerWidths[level] = 0;
 
@@ -88,6 +90,8 @@
 		// Adjust positions based on siblings count to centralize vertical spacing
 		Object.keys(history.messages).forEach((id) => {
 			const pos = positionMap.get(id);
+			if (!pos) return;
+
 			const x = direction === 'vertical' ? pos.position * siblingOffset : pos.level * levelOffset;
 			const y = direction === 'vertical' ? pos.level * levelOffset : pos.position * siblingOffset;