Handle cases when inspect.stack() fails

scrapy/utils/deprecate.py

@@ -95,10 +95,18 @@ def create_deprecated_class(name, new_class, clsdict=None,
             return super(DeprecatedClass, cls).__call__(*args, **kwargs)
 
     deprecated_cls = DeprecatedClass(name, (new_class,), clsdict or {})
-    frm = inspect.stack()[1]
-    parent_module = inspect.getmodule(frm[0])
-    if parent_module is not None:
-        deprecated_cls.__module__ = parent_module.__name__
+
+    try:
+        frm = inspect.stack()[1]
+        parent_module = inspect.getmodule(frm[0])
+        if parent_module is not None:
+            deprecated_cls.__module__ = parent_module.__name__
+    except Exception as e:
+        # Sometimes inspect.stack() fails (e.g. when the first import of
+        # deprecated class is in jinja2 template). __module__ attribute is not
+        # important enough to raise an exception as users may be unable
+        # to fix inspect.stack() errors.
+        warnings.warn("Error detecting parent module: %r" % e)
 
     return deprecated_cls