fix compiler crash during type inference of indexed ctuples

Cython/Compiler/ExprNodes.py

@@ -2924,6 +2924,7 @@ class IndexNode(ExprNode):
             elif base_type.is_ptr or base_type.is_array:
                 return base_type.base_type
             elif base_type.is_ctuple and isinstance(self.index, IntNode):
+                if self.index.has_constant_result():
                     index = self.index.constant_result
                     if index < 0:
                         index += base_type.size