make stream shutdown if self-node has been removed (#2125)

* add shutdown that asserts if headscale had panics

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* add test case producing 2118 panic

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* make stream shutdown if self-node has been removed

Currently we will read the node from database, and since it is
deleted, the id might be set to nil. Keep the node around and
just shutdown, so it is cleanly removed from notifier.

Fixes #2118

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

---------

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

integration/dockertestutil/logs.go

@@ -17,10 +17,10 @@ func SaveLog(
 	pool *dockertest.Pool,
 	resource *dockertest.Resource,
 	basePath string,
-) error {
+) (string, string, error) {
 	err := os.MkdirAll(basePath, os.ModePerm)
 	if err != nil {
-		return err
+		return "", "", err
 	}
 
 	var stdout bytes.Buffer
@@ -41,28 +41,30 @@ func SaveLog(
 		},
 	)
 	if err != nil {
-		return err
+		return "", "", err
 	}
 
 	log.Printf("Saving logs for %s to %s\n", resource.Container.Name, basePath)
 
+	stdoutPath := path.Join(basePath, resource.Container.Name+".stdout.log")
 	err = os.WriteFile(
-		path.Join(basePath, resource.Container.Name+".stdout.log"),
+		stdoutPath,
 		stdout.Bytes(),
 		filePerm,
 	)
 	if err != nil {
-		return err
+		return "", "", err
 	}
 
+	stderrPath := path.Join(basePath, resource.Container.Name+".stderr.log")
 	err = os.WriteFile(
-		path.Join(basePath, resource.Container.Name+".stderr.log"),
+		stderrPath,
 		stderr.Bytes(),
 		filePerm,
 	)
 	if err != nil {
-		return err
+		return "", "", err
 	}
 
-	return nil
+	return stdoutPath, stderrPath, nil
 }