fix: asset validation on mintFeeShares (#1070)

Author: yan-man

snapshots/Hub.Operations.json

@@ -4,7 +4,7 @@
   "draw": "105931",
   "eliminateDeficit: full": "59781",
   "eliminateDeficit: partial": "69429",
-  "mintFeeShares": "84007",
+  "mintFeeShares": "86130",
   "payFee": "72302",
   "refreshPremium": "71999",
   "remove: full": "76993",

src/hub/Hub.sol

@@ -206,6 +206,7 @@ contract Hub is IHub, AccessManaged {
 
   /// @inheritdoc IHub
   function mintFeeShares(uint256 assetId) external restricted returns (uint256) {
+    require(assetId < _assetCount, AssetNotListed());
     Asset storage asset = _assets[assetId];
     asset.accrue();
     uint256 feeShares = _mintFeeShares(asset, assetId);

tests/unit/Hub/Hub.MintFeeShares.t.sol

@@ -31,6 +31,12 @@ contract HubMintFeeSharesTest is HubBase {
     Utils.mintFeeShares(hub1, daiAssetId, ADMIN);
   }
 
+  function test_mintFeeShares_revertsWith_AssetNotListed() public {
+    uint256 invalidAssetId = hub1.getAssetCount();
+    vm.expectRevert(IHub.AssetNotListed.selector);
+    Utils.mintFeeShares(hub1, invalidAssetId, ADMIN);
+  }
+
   function test_mintFeeShares() public {
     // Create debt to build up fees on the existing treasury spoke
     _addAndDrawLiquidity({