Remove hyperopt-loss default option

Force users to make a concious choice on a hyperopt-loss function

freqtrade/resolvers/hyperopt_resolver.py

@@ -7,7 +7,7 @@ import logging
 from pathlib import Path
 from typing import Dict
 
-from freqtrade.constants import DEFAULT_HYPEROPT_LOSS, USERPATH_HYPEROPTS
+from freqtrade.constants import USERPATH_HYPEROPTS
 from freqtrade.exceptions import OperationalException
 from freqtrade.optimize.hyperopt_interface import IHyperOpt
 from freqtrade.optimize.hyperopt_loss_interface import IHyperOptLoss
@@ -70,10 +70,10 @@ class HyperOptLossResolver(IResolver):
         :param config: configuration dictionary
         """
 
-        # Verify the hyperopt_loss is in the configuration, otherwise fallback to the
-        # default hyperopt loss
-        hyperoptloss_name = config.get('hyperopt_loss') or DEFAULT_HYPEROPT_LOSS
-
+        hyperoptloss_name = config.get('hyperopt_loss')
+        if not hyperoptloss_name:
+            raise OperationalException("No Hyperopt loss set. Please use `--hyperopt-loss` to "
+                                       "specify the Hyperopt-Loss class to use.")
         hyperoptloss = HyperOptLossResolver.load_object(hyperoptloss_name,
                                                         config, kwargs={},
                                                         extra_dir=config.get('hyperopt_path'))