Small tweaks, respect image data path configuration

src/calng/DetectorAssembler.py

 import enum
 from timeit import default_timer
-import functools
 import re
 
 from karabo.bound import (
@@ -98,11 +97,17 @@ class DetectorAssembler(TrainMatcher.TrainMatcher):
             .commit(),
 
             STRING_ELEMENT(expected)
-            .key("pathToStack")
+            .key("imageDataPath")
             .assignmentOptional()
             .defaultValue("image.data")
             .commit(),
 
+            STRING_ELEMENT(expected)
+            .key("imageMaskPath")
+            .assignmentOptional()
+            .defaultValue("image.mask")
+            .commit(),
+
             OUTPUT_CHANNEL(expected)
             .key("assembledOutput")
             .dataSchema(schemas.preview_schema(wrap_image_in_imagedata=False))
@@ -191,7 +196,8 @@ class DetectorAssembler(TrainMatcher.TrainMatcher):
         super().initialization()
 
         self._preview_friend = preview_utils.PreviewFriend(self)
-        self._path_to_stack = self.get("pathToStack")
+        self._image_data_path = self.get("imageDataPath")
+        self._image_mask_path = self.get("imageMaskPath")
         self._geometry = None
         self._stack_input_buffer = None
         # set up source to index mapping
@@ -331,8 +337,6 @@ class DetectorAssembler(TrainMatcher.TrainMatcher):
         earliest_source_timestamp = float("inf")
         self._stack_input_buffer.mask.fill(False)
         for source, (data, source_timestamp) in sources.items():
-            if source not in self._source_to_index:
-                continue
             # regular TrainMatcher output
             self.output.write(
                 data, ChannelMetaData(source, source_timestamp), copyAllData=False
@@ -340,15 +344,19 @@ class DetectorAssembler(TrainMatcher.TrainMatcher):
             if bridge_output_choice is BridgeOutputOptions.MATCHED:
                 self.zmq_output.write(source, data, source_timestamp)
 
+            if source not in self._source_to_index:
+                continue
             # prepare for assembly
             # TODO: handle failure to "parse" source, get data out
-            image_data = data["image.data"]
+            if not data.has(self._image_data_path):
+                continue
+            image_data = data[self._image_data_path]
             if isinstance(image_data, ImageData):
                 # TODO: maybe glance encoding here
                 image_data = image_data.getData()
             image_data = image_data.astype(np.float32, copy=False)  # TODO: set dtype based on input?
-            if data.has("image.mask"):
-                image_mask = data["image.mask"]
+            if data.has(self._image_mask_path):
+                image_mask = data[self._image_mask_path]
                 if isinstance(image_mask, ImageData):
                     image_mask = image_mask.getData()
             else: