fix: user is not a field (#24129)

diff --git a/erpnext/non_profit/doctype/member/member.py b/erpnext/non_profit/doctype/member/member.py
index 44b975e..25d6b53 100644
--- a/erpnext/non_profit/doctype/member/member.py
+++ b/erpnext/non_profit/doctype/member/member.py
@@ -59,7 +59,7 @@
 			frappe.msgprint(_("A customer is already linked to this Member"))
 		cust = create_customer(frappe._dict({
 			'fullname': self.member_name,
-			'email': self.email_id or self.user,
+			'email': self.email_id or self.email,
 			'phone': None
 		}))
 
@@ -177,4 +177,4 @@
 			mobile=mobile
 		))
 
-		return member.name
\ No newline at end of file
+		return member.name