Give a more helpful error message if a service is created with an unknown user ID

src/github.com/matrix-org/go-neb/clients/clients.go

@@ -1,6 +1,8 @@
 package clients
 
 import (
+	"database/sql"
+	"fmt"
 	"net/http"
 	"strings"
 	"sync"
@@ -94,6 +96,9 @@ func (c *Clients) loadClientFromDB(userID string) (entry clientEntry, err error)
 	}
 
 	if entry.config, err = c.db.LoadMatrixClientConfig(userID); err != nil {
+		if err == sql.ErrNoRows {
+			err = fmt.Errorf("client with user ID %s does not exist", userID)
+		}
 		return
 	}
 

src/github.com/matrix-org/go-neb/database/schema.go

@@ -4,9 +4,10 @@ import (
 	"database/sql"
 	"encoding/json"
 	"fmt"
+	"time"
+
 	"github.com/matrix-org/go-neb/api"
 	"github.com/matrix-org/go-neb/types"
-	"time"
 )
 
 const schemaSQL = `

src/github.com/matrix-org/go-neb/server/server_test.go

@@ -10,8 +10,7 @@ func TestProtect(t *testing.T) {
 	mockWriter := httptest.NewRecorder()
 	mockReq, _ := http.NewRequest("GET", "http://example.com/foo", nil)
 	h := Protect(func(w http.ResponseWriter, req *http.Request) {
-		var array []string
-		w.Write([]byte(array[5])) // NPE
+		panic("oh noes!")
 	})
 
 	h(mockWriter, mockReq)