diff --git a/qnt/backtester.py b/qnt/backtester.py
index f010186..b1550f9 100644
--- a/qnt/backtester.py
+++ b/qnt/backtester.py
@@ -285,15 +285,7 @@ def backtest(
         current_date = pd.to_datetime('today')
         data_days_difference = (current_date - checking_start_data_date).days
         data = load_data(data_days_difference)
-        try:
-            if data.name == 'stocks' and competition_type != 'stocks' and competition_type != 'stocks_long' \
-                    or data.name == 'stocks_nasdaq100' and competition_type != 'stocks_nasdaq100' \
-                    or data.name == 'cryptofutures' and competition_type != 'cryptofutures' and competition_type != 'crypto_futures' \
-                    or data.name == 'crypto' and competition_type != 'crypto' \
-                    or data.name == 'futures' and competition_type != 'futures':
-                log_err("WARNING! The data type and the competition type are mismatch.")
-        except:
-            pass
+        check_data_type_mismatch(data, competition_type)
         data, time_series = extract_time_series(data)
 
         log_info("Run strategy...")
@@ -309,15 +301,7 @@ def backtest(
             days=60)))
     else:
         data = load_data(lookback_period)
-        try:
-            if data.name == 'stocks' and competition_type != 'stocks' and competition_type != 'stocks_long' \
-                    or data.name == 'stocks_nasdaq100' and competition_type != 'stocks_nasdaq100' \
-                    or data.name == 'cryptofutures' and competition_type != 'cryptofutures' and competition_type != 'crypto_futures' \
-                    or data.name == 'crypto' and competition_type != 'crypto' \
-                    or data.name == 'futures' and competition_type != 'futures':
-                log_err("WARNING! The data type and the competition type are mismatch.")
-        except:
-            pass
+        check_data_type_mismatch(data, competition_type)
         data, time_series = extract_time_series(data)
 
         log_info("Run strategy...")
@@ -418,32 +402,20 @@ def copy_window(data, dt, tail):
     output_time_coord = ts[ts >= start_date]
     output_time_coord = output_time_coord[::step]
 
-    i = 0
-
-    sys.stdout.flush()
-
     with progressbar.ProgressBar(max_value=len(output_time_coord), poll_interval=1) as p:
         state = None
-        for t in output_time_coord:
+        for i, t in enumerate(output_time_coord):
             tail = copy_window(data, t, lookback_period)
             result = strategy(tail, copy.deepcopy(state))
             output, state = unpack_result(result)
-            if type(output) != xr.DataArray:
-                log_err("Output is not xarray!")
-                return
-            if set(output.dims) != {'asset'} and set(output.dims) != {'asset', 'time'}:
-                log_err("Wrong output dimensions. ", output.dims, "Should contain only:", {'asset', 'time'})
-                return
+            validate_output(output)
             if 'time' in output.dims:
-                output = output.sel(time=t)
+                output = output.isel(time=-1)
             output = output.drop_vars(['field', 'time'], errors='ignore')
             outputs.append(output)
             if collect_all_states:
                 all_states.append(state)
-            i += 1
-            p.update(i)
-
-    sys.stderr.flush()
+            p.update(i+1)
 
     log_info("Merge outputs...")
     output = xr.concat(outputs, pd.Index(output_time_coord, name=qndata.ds.TIME))
@@ -451,6 +423,25 @@ def copy_window(data, dt, tail):
     return output, all_states if collect_all_states else state
 
 
+def check_data_type_mismatch(data, competition_type: str):
+    valid_competition_types = {
+        'stocks': ['stocks', 'stocks_long'],
+        'stocks_nasdaq100': ['stocks_nasdaq100'],
+        'cryptofutures': ['cryptofutures', 'crypto_futures'],
+        'crypto': ['crypto'],
+        'futures': ['futures']
+    }
+    if competition_type not in valid_competition_types[data.name]:
+        log_err("WARNING! The data type and the competition type are mismatched.")
+
+
+def validate_output(output):
+    if not isinstance(output, xr.DataArray):
+        raise ValueError("Invalid output type. Expected xarray.DataArray.")
+    if set(output.dims) not in [{'asset'}, {'asset', 'time'}]:
+        raise ValueError(f"Wrong output dimensions. {output.dims} Should contain only: {'asset', 'time'}")
+
+
 def standard_window(data, max_date: np.datetime64, lookback_period:int):
     min_date = max_date - np.timedelta64(lookback_period,'D')
     return data.loc[dict(time=slice(min_date, max_date))]