Fix: define SparseArray even is sparse not available to avoid import error

Author: balbasty

spm/__wrapper__.py

@@ -1166,6 +1166,10 @@ def from_any(cls, other, **kwargs) -> "SparseArray":
             return other
 
 
+else:
+    WrappedSparseArray = SparseArray = None
+
+
 # ----------------------------------------------------------------------
 # Array
 # ----------------------------------------------------------------------