Continuation crash (#777)

I didn't get the feedback on the actual runtime errors yet, but I
believe it's still worth merging - as a decent technical change
(removing `Unsafe...`).

I don't see any obvious mistakes in the existing code either.

Author: pblazej

Sources/LiveKit/Support/AsyncCompleter.swift

@@ -66,7 +66,7 @@ actor CompleterMapActor<T: Sendable> {
 final class AsyncCompleter<T: Sendable>: @unchecked Sendable, Loggable {
     //
     struct WaitEntry {
-        let continuation: UnsafeContinuation<T, Error>
+        let continuation: CheckedContinuation<T, Error>
         let timeoutBlock: DispatchWorkItem
 
         func cancel() {
@@ -123,6 +123,10 @@ final class AsyncCompleter<T: Sendable>: @unchecked Sendable, Loggable {
 
     func resume(with result: Result<T, Error>) {
         _lock.sync {
+            if let _result {
+                log("\(label) already resolved \(_entries) with \(_result)", .debug)
+            }
+
             for entry in _entries.values {
                 entry.resume(with: result)
             }
@@ -160,7 +164,7 @@ final class AsyncCompleter<T: Sendable>: @unchecked Sendable, Loggable {
 
         // Create a cancel-aware timed continuation
         return try await withTaskCancellationHandler {
-            try await withUnsafeThrowingContinuation { continuation in
+            try await withCheckedThrowingContinuation { continuation in
                 // Create time-out block
                 let timeoutBlock = DispatchWorkItem { [weak self] in
                     guard let self else { return }