fix cagr on zero or negative values

freqtrade/data/metrics.py

@@ -296,7 +296,7 @@ def calculate_cagr(days_passed: int, starting_balance: float, final_balance: flo
     :param final_balance: Final balance to calculate CAGR against
     :return: CAGR
     """
-    if final_balance < 0:
+    if (final_balance < 0) or (starting_balance <= 0) or (days_passed <= 0):
         # With leveraged trades, final_balance can become negative.
         return 0
     return (final_balance / starting_balance) ** (1 / (days_passed / 365)) - 1

tests/data/test_btanalysis.py

@@ -516,6 +516,8 @@ def test_calculate_sqn_cases(profits, starting_balance, expected_sqn, descriptio
         (1000, 1500, 365, 0.5),
         (1000, 1500, 100, 3.3927),  # sub year
         (0.01000000, 0.01762792, 120, 4.6087),  # sub year BTC values
+        (1000, 1010, 0, 0.0),  # zero days
+        (-100, 100, 365, 0.0),  # negative starting balance
     ],
 )
 def test_calculate_cagr(start, end, days, expected):