Merge contour_px < 2 rejection into single branch

Author: timtreis

src/spatialdata_plot/pl/utils.py

@@ -2368,14 +2368,11 @@ def _type_check_params(param_dict: dict[str, Any], element_type: str) -> dict[st
         else:
             param_dict["outline_color"] = Color(outline_color)
 
-    if contour_px is not None:
-        if contour_px <= 0:
-            raise ValueError("Parameter 'contour_px' must be a positive number.")
-        if contour_px == 1:
-            raise ValueError(
-                "Parameter 'contour_px' must be >= 2; contour_px=1 produces no visible outline "
-                "(a 1x1 erosion is the identity transformation)."
-            )
+    if contour_px is not None and contour_px < 2:
+        raise ValueError(
+            "Parameter 'contour_px' must be >= 2; values below 2 produce no visible outline "
+            "(a 1x1 erosion is the identity transformation)."
+        )
 
     alpha = param_dict.get("alpha")
     if alpha is not None: