Correct undefined var

app.py

@@ -47,6 +47,8 @@ def yf_get_ticker_price(ticker: str) -> float:
     Args:
         ticker: A string representing a stock ticker.
     """
+    stock = yf.Ticker(ticker)
+
     # Get current underlying price
     hist = stock.history(period="1d")
     if hist.empty:
@@ -82,7 +84,7 @@ def yf_get_atm_straddle_price(ticker: str, dte: int = 0) -> Dict[str, Any]:
     stock = yf.Ticker(ticker)
 
     # Get current underlying price
-    underlying_price = yf_get_ticker_price(ticker)
+    underlying_price = yf_get_ticker_price(stock)
 
     # Get option expiration dates
     expirations = stock.options