3 files changed, 4 insertions, 2 deletions

diff --git a/pyecsca/sca/attack/CPA.py b/pyecsca/sca/attack/CPA.py
index 77c9abb..6efa3b5 100644
--- a/pyecsca/sca/attack/CPA.py
+++ b/pyecsca/sca/attack/CPA.py
@@ -55,7 +55,7 @@ class CPA:
                 action_index += 2
             elif bit == "0":
                 action_index += 1
-        result = ctx.actions.get_by_index([0, action_index])[0]
+        result = ctx.actions.get_by_index([action_index]).action
         return result.output_points[0].X
 
     def compute_correlation_trace(
diff --git a/pyecsca/sca/attack/DPA.py b/pyecsca/sca/attack/DPA.py
index 661adc6..da4ae65 100644
--- a/pyecsca/sca/attack/DPA.py
+++ b/pyecsca/sca/attack/DPA.py
@@ -50,7 +50,7 @@ class DPA:
                 action_index += 2
             elif bit == "0":
                 action_index += 1
-        result = ctx.actions.get_by_index([0, action_index])[0]
+        result = ctx.actions.get_by_index([action_index]).action
         return result.output_points[0]
 
     def split_traces(
diff --git a/pyecsca/sca/target/leakage.py b/pyecsca/sca/target/leakage.py
index c832028..e8734fb 100644
--- a/pyecsca/sca/target/leakage.py
+++ b/pyecsca/sca/target/leakage.py
@@ -52,6 +52,8 @@ class LeakageTarget(Target):
                     temp_trace.append(leak)
 
         temp_trace: list[int] = []
+        if not context.actions:
+            raise ValueError("Empty context")
         context.actions.walk(callback)
         return Trace(np.array(temp_trace))