Crash in `NetworkTransport` on reconnect

[nighthawk]

Describe the bug
Came across a runtime crash in NetworkTransport when a MCP client reconnects (mcp-swift-sdk version 0.9.0)

To Reproduce
I haven't yet been able to reliably reproduce it. In my case the host macOS app was running, when I launched Zed where I had the MCP server configured. Zed seems to reconnect, but that caused a runtime crash in the host macOS app.

Logs

macOS crash log snippet:

0x1a76fa1f8 _assertionFailure(_:_:file:line:flags:) + 176
1   libswift_Concurrency.dylib    	       0x27ecd64e4 CheckedContinuation.resume(throwing:) + 348
2   MyHostApp                      	       0x1003beb94 closure #1 in NetworkTransport.handleReconnection(error:continuation:context:) + 180

Relevant code snippet:

        private func handleReconnection(
            error: Swift.Error,
            continuation: CheckedContinuation<Void, Swift.Error>,
            context: String
        ) async {
            if !isStopping,
                reconnectionConfig.enabled,
                reconnectAttempt < reconnectionConfig.maxAttempts
            {
                // Try to reconnect with exponential backoff
                reconnectAttempt += 1
                logger.info(
                    "Attempting reconnection after \(context) (\(reconnectAttempt)/\(reconnectionConfig.maxAttempts))..."
                )

                // Calculate backoff delay
                let delay = reconnectionConfig.backoffDelay(for: reconnectAttempt)

                // Schedule reconnection attempt after delay
                Task {
                    try? await Task.sleep(for: .seconds(delay))
                    if !isStopping {
                        // Cancel the current connection before attempting to reconnect.
                        self.connection.cancel()
                        // Resume original continuation with error; outer logic or a new call to connect() will handle retry.
                        continuation.resume(throwing: error)
                    } else {
                        continuation.resume(throwing: error)  // Stopping, so fail.
                    }
                }
            } else {
                // Not configured to reconnect, exceeded max attempts, or stopping
                self.connection.cancel()  // Ensure connection is cancelled
                continuation.resume(throwing: error)
            }
        }

Additional context

The crash is triggered when continuation.resume(throwing: ...) gets called multiple times for the same continuation. I haven't yet wrapped my head around the entire flow here and how this is possible, and it's hard to debug as it seems intermittent.

Suggestions appreciated for how to address this.

[provencher]

Ran into the same issue

[nighthawk]

Re-opening as I only merged that in my fork. It isn't yet merged in this repo. I've opened #147 for that.