try safer http cleanup on page deinit

src/http/Client.zig

@@ -153,7 +153,7 @@ pub fn abort(self: *Client) void {
             log.err(.http, "get private info", .{ .err = err, .source = "abort" });
             continue;
         };
-        transfer.abort();
+        transfer.kill();
     }
     std.debug.assert(self.active == 0);
 
@@ -812,6 +812,15 @@ pub const Transfer = struct {
         self.deinit();
     }
 
+    // internal, when the page is shutting down. Doesn't have the same ceremony
+    // as abort (doesn't send a notification, doesn't invoke an error callback)
+    fn kill(self: *Transfer) void {
+        if (self._handle != null) {
+            self.client.endTransfer(self);
+        }
+        self.deinit();
+    }
+
     // abortAuthChallenge is called when an auth chanllenge interception is
     // abort. We don't call self.client.endTransfer here b/c it has been done
     // before interception process.