fix: Release Manager internal review fixes (#1571)

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**Motivation:**

After an internal security review, a few helpful fixes were determined
for code clarity and reduced complexity.

**Modifications:**

* Reduced complexity for publishing release
* More appropriate function visibility

**Result:**

Cleaner, safer code

Author: nadir-akhtar

src/contracts/core/ReleaseManager.sol

@@ -40,12 +40,7 @@ contract ReleaseManager is Initializable, ReleaseManagerStorage, PermissionContr
         // New release id is the length of the array before this call.
         releaseId = releases.length;
         // Increment total releases for this operator set.
-        releases.push();
-        // Copy the release to storage.
-        for (uint256 i = 0; i < release.artifacts.length; ++i) {
-            releases[releaseId].artifacts.push(release.artifacts[i]);
-        }
-        releases[releaseId].upgradeByTime = release.upgradeByTime;
+        releases.push(release);
 
         emit ReleasePublished(operatorSet, releaseId, release);
     }
@@ -81,8 +76,10 @@ contract ReleaseManager is Initializable, ReleaseManagerStorage, PermissionContr
     /// @inheritdoc IReleaseManager
     function getLatestRelease(
         OperatorSet memory operatorSet
-    ) public view returns (uint256, Release memory) {
+    ) external view returns (uint256, Release memory) {
         Release[] storage releases = _operatorSetReleases[operatorSet.key()];
+        require(releases.length > 0, NoReleases());
+
         uint256 latestReleaseId = releases.length - 1;
         return (latestReleaseId, releases[latestReleaseId]);
     }

src/contracts/core/ReleaseManagerStorage.sol

@@ -18,5 +18,5 @@ abstract contract ReleaseManagerStorage is IReleaseManager {
      * variables without shifting down storage in the inheritance chain.
      * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
      */
-    uint256[49] private __gap;
+    uint256[48] private __gap;
 }

src/contracts/interfaces/IReleaseManager.sol

@@ -12,6 +12,9 @@ interface IReleaseManagerErrors {
 
     /// @notice Thrown when the metadata URI is empty.
     error InvalidMetadataURI();
+
+    /// @notice Thrown when there are no releases for an operator set.
+    error NoReleases();
 }
 
 interface IReleaseManagerTypes {