Add output buffering for rendered pages

cmd/boardvoting/handlers.go

@@ -18,6 +18,7 @@ limitations under the License.
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"html/template"
 	"io/fs"
@@ -78,12 +79,18 @@ func (app *application) render(w http.ResponseWriter, status int, page string, d
 		return
 	}
 
-	w.WriteHeader(status)
+	buf := new(bytes.Buffer)
 
-	err := ts.ExecuteTemplate(w, "base", data)
+	err := ts.ExecuteTemplate(buf, "base", data)
 	if err != nil {
 		app.serverError(w, err)
+
+		return
 	}
+
+	w.WriteHeader(status)
+
+	_, _ = buf.WriteTo(w)
 }
 
 type motionListTemplateData struct {