fix: prevent new conversation action when no messages are present

Author: Kingshuk-Microsoft

content-gen/src/app/frontend/src/components/ChatHistory.tsx

@@ -279,15 +279,15 @@ export function ChatHistory({
             </Link>
           )}
           <Link
-            onClick={isGenerating ? undefined : onNewConversation}
+            onClick={(isGenerating || currentMessages.length === 0) ? undefined : onNewConversation}
             style={{
               display: 'flex',
               alignItems: 'center',
               gap: '8px',
               fontSize: '13px',
-              color: isGenerating ? tokens.colorNeutralForegroundDisabled : tokens.colorNeutralForeground1,
-              cursor: isGenerating ? 'not-allowed' : 'pointer',
-              pointerEvents: isGenerating ? 'none' : 'auto',
+              color: (isGenerating || currentMessages.length === 0) ? tokens.colorNeutralForegroundDisabled : tokens.colorNeutralForeground1,
+              cursor: (isGenerating || currentMessages.length === 0) ? 'not-allowed' : 'pointer',
+              pointerEvents: (isGenerating || currentMessages.length === 0) ? 'none' : 'auto',
             }}
           >
             <Compose20Regular />

content-gen/src/app/frontend/src/components/ChatPanel.tsx

@@ -286,7 +286,7 @@ export function ChatPanel({
                 icon={<Add20Regular />}
                 size="small"
                 onClick={onNewConversation}
-                disabled={isLoading}
+                disabled={isLoading || messages.length === 0}
                 style={{ 
                   minWidth: '32px',
                   height: '32px',