fix: Prevent short positions with non-UUSDC assets as collateral

front_end_script/README.md

@@ -161,7 +161,13 @@ createMarginOrder(
 #### Exemple
 
 ```javascript
-createMarginOrder("short", { denom: "BTC", amount: "2" }, "4.3", "ETH", "2.2");
+createMarginOrder(
+  "short",
+  { denom: "uusdc", amount: "2002" },
+  "4.3",
+  "ueth",
+  "2.2"
+);
 ```
 
 ### 7. cancelMarginOrder(order_id)

src/action/execute/create_margin_order.rs

@@ -1,4 +1,4 @@
-use cosmwasm_std::{to_json_binary, Coin, Decimal, Int128, SubMsg};
+use cosmwasm_std::{to_json_binary, Coin, Decimal, Int128, StdError, SubMsg};
 
 use crate::msg::ReplyType;
 
@@ -21,6 +21,12 @@ pub fn create_margin_order(
         return Err(ContractError::CollateralAmount);
     }
 
+    if position == MarginPosition::Short && collateral.denom == "uusdc" {
+        return Err(
+            StdError::generic_err("the collateral asset for a short can only be USDC").into(),
+        );
+    }
+
     cw_utils::must_pay(&info, &info.funds[0].denom)?;
 
     let borrow_token = Coin {