Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: jholveck

src/mss/linux/base.py

@@ -271,12 +271,16 @@ def _randr_output_ids(
                         edid_params["mfr_date"] = f"{edid_data['manufacture_year']:04d}"
                 if "model_year" in edid_data:
                     edid_params["model_year"] = f"{edid_data['model_year']:04d}"
-                rv["unique_id"] = urlencode(edid_params)
+                if edid_params:
+                    rv["unique_id"] = urlencode(edid_params)
 
         return rv
 
     @staticmethod
     def _choose_randr_output(outputs: Array[xcb.RandrOutput], primary_output: xcb.RandrOutput, /) -> xcb.RandrOutput:
+        if len(outputs) == 0:
+            msg = "No RandR outputs available"
+            raise ScreenShotError(msg)
         if any(o == primary_output for o in outputs):
             return primary_output
         return outputs[0]

src/mss/tools.py

@@ -23,7 +23,7 @@
 _EDID_DESCR_TAG_LOC = 3  # Location of display descriptor tag
 _EDID_DESCR_TAG_SN = 0xFF  # Descriptor is a string serial number
 _EDID_DESCR_TAG_NAME = 0xFC  # Descriptor is a string model name
-_EDID_DESCR_STR_LOC = slice(5, 19)  # Location of string in a display descriptor
+_EDID_DESCR_STR_LOC = slice(5, 18)  # Location of string in a display descriptor
 
 
 def parse_edid(edid_data: bytes) -> dict: