refactor: replace getPrice with getPriceNoOlderThan (#24)

Author: ali-behjati

express-relay/easy_lend/contracts/EasyLend.sol

@@ -85,7 +85,8 @@ contract EasyLend is IExpressRelayFeeReceiver {
      */
     function _getPrice(bytes32 id) internal view returns (uint256) {
         IPyth oracle = IPyth(payable(_oracle));
-        return convertToUint(oracle.getPrice(id), 18);
+        // Get the price if it is not older than 60 seconds.
+        return convertToUint(oracle.getPriceNoOlderThan(id, 60), 18);
     }
 
     function getAllowUndercollateralized() public view returns (bool) {

price_feeds/evm/my_first_pyth_app/contracts/src/MyFirstPythContract.sol

@@ -14,7 +14,8 @@ contract MyFirstPythContract {
   }
 
   function mint() public payable {
-    PythStructs.Price memory price = pyth.getPrice(ethUsdPriceId);
+    // Get the price if it is not older than 60 seconds.
+    PythStructs.Price memory price = pyth.getPriceNoOlderThan(ethUsdPriceId, 60);
 
     uint ethPrice18Decimals = (uint(uint64(price.price)) * (10 ** 18)) /
       (10 ** uint8(uint32(-1 * price.expo)));
@@ -41,4 +42,4 @@ contract MyFirstPythContract {
   // Error raised if the payment is not sufficient
   error InsufficientFee();
 }
- 
+ 

price_feeds/evm/oracle_swap/contract/src/OracleSwap.sol

@@ -65,11 +65,14 @@ contract OracleSwap {
         uint256 updateFee = pyth.getUpdateFee(pythUpdateData);
         pyth.updatePriceFeeds{value: updateFee}(pythUpdateData);
 
-        PythStructs.Price memory currentBasePrice = pyth.getPrice(
-            baseTokenPriceId
+        // Get the prices if they are not older than 60 seconds.
+        PythStructs.Price memory currentBasePrice = pyth.getPriceNoOlderThan(
+            baseTokenPriceId,
+            60
         );
-        PythStructs.Price memory currentQuotePrice = pyth.getPrice(
-            quoteTokenPriceId
+        PythStructs.Price memory currentQuotePrice = pyth.getPriceNoOlderThan(
+            quoteTokenPriceId,
+            60
         );
 
         // Note: this code does all arithmetic with 18 decimal points. This approach should be fine for most