Merge pull request #320 from Dana-Farber-AIOS/informative-error-message

Make error message for extract_region more informative
Dana-Farber-AIOS · Jul 4, 2022 · 3e13d2b · 3e13d2b
2 parents f635514 + eab3ceb
commit 3e13d2b
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/pathml/core/slide_data.py b/pathml/core/slide_data.py
@@ -379,6 +379,12 @@ def extract_region(self, location, size, *args, **kwargs):
         Returns:
             np.ndarray: image at the specified region
         """
+        if self.slide is None:
+            raise ValueError(
+                "Cannot call `.extract_region()` because no slide is specified. "
+                "If already tiled, access `.tiles` directly instead"
+            )
+
         return self.slide.extract_region(location, size, *args, **kwargs)
 
     def generate_tiles(self, shape=3000, stride=None, pad=False, **kwargs):