Add comment to error handling

Author: nicholasdalhaug

src/isar/robot/robot_pause_mission.py

@@ -42,6 +42,8 @@ def robot_pause_mission(
             continue
         return None
 
+    # error is always set when the loop exits without returning — every iteration
+    # either returns early or assigns error before continuing
     assert error is not None
     error_description = (
         f"\nFailed to pause the robot after {retries} attempts because: "

src/isar/robot/robot_resume_mission.py

@@ -45,6 +45,8 @@ def robot_resume_mission(
             retries += 1
             continue
 
+    # error is always set when the loop exits without returning — every iteration
+    # either returns early or assigns error before continuing
     assert error is not None
     error_description = (
         f"\nFailed to resume the robot after {retries + 1} attempts because: "

src/isar/robot/robot_stop_mission.py

@@ -43,6 +43,8 @@ def robot_stop_mission(
             continue
         return None
 
+    # error is always set when the loop exits without returning — every iteration
+    # either returns early or assigns error before continuing
     assert error is not None
     error_description = (
         f"\nFailed to stop the robot after {retries} attempts because: "