Timer.record(_ duration:) review feedback cleanup

Sources/Metrics/Metrics.swift

@@ -76,11 +76,6 @@ extension Timer {
 }
 
 #if swift(>=5.7)
-
-public enum TimerError: Error {
-    case durationToIntOverflow
-}
-
 extension Timer {
     /// Convenience for recording a duration based on ``Duration``.
     ///

Tests/MetricsTests/MetricsTests.swift

@@ -101,7 +101,7 @@ class MetricsExtensionsTests: XCTestCase {
         // tests on Linux in MetricsTests+XCTest don't complain that the func does not exist.
         #if swift(>=5.7)
         guard #available(iOS 16, macOS 13, tvOS 15, watchOS 8, *) else {
-            return
+            throw XCTSkip("Timer.record(_ duration: Duration) is available on Swift 5.7+")
         }
 
         let metrics = TestMetrics()