fix: make context cancel unconditional in flush (#15)

The context cancel function was declared and deferred inside a
conditional block. A defer inside a conditional is correct but subtle —
particularly if the closure were later refactored to use named returns,
the cancel call would silently move. Initialize cancel to a no-op func
upfront so the defer is always unconditional and its scope is obvious at
a glance.

Co-authored-by: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: acoshift

quickwit.go

@@ -221,11 +221,11 @@ func (c *Client) loop() {
 		}
 
 		ctx := context.Background()
+		cancel := context.CancelFunc(func() {})
 		if t := c.getIngestTimeout(); t != 0 {
-			var cancel context.CancelFunc
 			ctx, cancel = context.WithTimeout(ctx, t)
-			defer cancel()
 		}
+		defer cancel()
 		req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewReader(buf.Bytes()))
 		if err != nil {
 			return false