Handle pure scalars in new_expr

Author: Luke Shaw

src/blosc2/lazyexpr.py

@@ -3128,6 +3128,9 @@ def _new_expr(cls, expression, operands, guess, out=None, where=None, ne_args=No
                 expression_, operands_ = conserve_functions(
                     _expression, _operands, new_expr.operands | local_vars
                 )
+            elif _shape == () and not _operands:  # passed scalars
+                expression_ = "o0"
+                operands_ = {"o0": ne_evaluate(_expression)}
             else:
                 # An immediate evaluation happened
                 # (e.g. all operands are numpy arrays or constructors)