fix(dojo-lang): raise an error on value before key in model

crates/dojo/lang/src/attribute_macros/element.rs

@@ -41,9 +41,12 @@
     members: &[MemberAst],
     diagnostics: &mut Vec<PluginDiagnostic>,
 ) -> Vec<Member> {
+    let mut keys = true;
     members
         .iter()
         .filter_map(|member_ast| {
+            let key = member_ast.has_attr(db, "key");
+
             let member = Member {
                 name: member_ast.name(db).text(db).to_string(),
                 ty: member_ast
@@ -53,10 +56,23 @@
                     .get_text(db)
                     .trim()
                     .to_string(),
-                key: member_ast.has_attr(db, "key"),
+                key,
             };
 
             // validate key member
+            if key {
+                if !keys {
+                    diagnostics.push(PluginDiagnostic {
+                        message: "Key members must be defined before non-key members.".into(),
+                        stable_ptr: member_ast.name(db).stable_ptr().untyped(),
+                        severity: Severity::Error,
+                    });
+                    return None;
+                }
+            } else {
+                keys = false;
+            }
+
             if member.key && member.ty == "u256" {
                 diagnostics.push(PluginDiagnostic {
                     message: "Key is only supported for core types that are 1 felt long once \