Address review feedback from @jefferai

http/sys_health.go

@@ -2,6 +2,7 @@ package http
 
 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
 	"strconv"
 	"time"
@@ -121,6 +122,9 @@ func getSysHealth(core *vault.Core, r *http.Request) (int, *HealthResponse, erro
 		if err != nil {
 			return http.StatusInternalServerError, nil, err
 		}
+		if cluster == nil {
+			return http.StatusInternalServerError, nil, fmt.Errorf("failed to fetch cluster details")
+		}
 		clusterName = cluster.Name
 		clusterID = cluster.ID
 	}

http/sys_seal.go

@@ -159,6 +159,10 @@ func handleSysSealStatusRaw(core *vault.Core, w http.ResponseWriter, r *http.Req
 			respondError(w, http.StatusInternalServerError, err)
 			return
 		}
+		if cluster == nil {
+			respondError(w, http.StatusInternalServerError, fmt.Errorf("failed to fetch cluster details"))
+			return
+		}
 		clusterName = cluster.Name
 		clusterID = cluster.ID
 	}

vault/cluster.go

@@ -23,15 +23,14 @@ type Cluster struct {
 }
 
 // Cluster fetches the details of either local or global cluster based on the
-// input. This method errors out when Vault is sealed. This function never
-// returns a nil Cluster object.
+// input. This method errors out when Vault is sealed.
 func (c *Core) Cluster() (*Cluster, error) {
 	var cluster Cluster
 
 	// Fetch the storage entry. This call fails when Vault is sealed.
 	entry, err := c.barrier.Get(coreLocalClusterInfoPath)
 	if err != nil {
-		return &cluster, err
+		return nil, err
 	}
 	if entry == nil {
 		return &cluster, nil
@@ -39,7 +38,7 @@ func (c *Core) Cluster() (*Cluster, error) {
 
 	// Decode the cluster information
 	if err = jsonutil.DecodeJSON(entry.Value, &cluster); err != nil {
-		return &cluster, fmt.Errorf("failed to decode cluster details: %v", err)
+		return nil, fmt.Errorf("failed to decode cluster details: %v", err)
 	}
 
 	// Set in config file