Add controller error writer exception handling

controllers/controllers.go

@@ -2,12 +2,16 @@ package controllers
 
 import (
 	"encoding/json"
+	"github.com/sirupsen/logrus"
 	"net/http"
 )
 
 func writeError(w http.ResponseWriter, status int, errStr string) {
 	w.WriteHeader(status)
-	json.NewEncoder(w).Encode(struct {
+	err := json.NewEncoder(w).Encode(struct {
 		Error string `json:"error"`
 	}{errStr})
+	if err != nil {
+		logrus.Fatal("Could not write JSON response: ", err)
+	}
 }