Use Invocation errors for expected errors.

src/openflexure_microscope_server/scan_directories.py

@@ -19,6 +19,8 @@ from pydantic import (
     model_validator,
 )
 
+from labthings_fastapi.exceptions import InvocationError
+
 from openflexure_microscope_server.stitching import StitchingSettings
 from openflexure_microscope_server.utilities import make_name_safe, requires_lock
 
@@ -34,7 +36,7 @@ SCAN_DATA_FILENAME = "scan_data.json"
 SCAN_DATA_SCHEMA_VERSION = 2
 
 
-class NotEnoughFreeSpaceError(IOError):
+class NotEnoughFreeSpaceError(InvocationError):
     """An exception raised if there is not enough free space on disk to scan."""
 
 

src/openflexure_microscope_server/things/autofocus.py

@@ -713,11 +713,11 @@ class AutofocusThing(lt.Thing):
         return "success", capture_id
 
 
-class NotAPeakError(RuntimeError):
+class NotAPeakError(lt.exceptions.InvocationError):
     """The data to fit isn't a peak."""
 
 
-class NoFocusFoundError(RuntimeError):
+class NoFocusFoundError(lt.exceptions.InvocationError):
     """No focus found during looping Autofocus."""
 
 

src/openflexure_microscope_server/things/background_detect.py

@@ -19,11 +19,11 @@ SettingsType = TypeVar("SettingsType", bound=BaseModel)
 BackgroundType = TypeVar("BackgroundType", bound=BaseModel)
 
 
-class MissingBackgroundDataError(RuntimeError):
+class MissingBackgroundDataError(lt.exceptions.InvocationError):
     """An error raised if checking for sample without background data set."""
 
 
-class ChannelBlankError(RuntimeError):
+class ChannelBlankError(lt.exceptions.InvocationError):
     """An error raised if a channel has no measured standard deviation.
 
     This is not physical and usually means the camera has not yet booted or changed

src/openflexure_microscope_server/things/stage_measure.py

@@ -106,7 +106,7 @@ class RomDataTracker:
         return {axis: int(turning_loc), other_axis: other_coord, "z": int(turning_z)}
 
 
-class ParasiticMotionError(Exception):
+class ParasiticMotionError(lt.exceptions.InvocationError):
     """Custom exception raised when parasitic motion is detected.
 
     Parasitic motion is when motion in the direction not being measured