errcheck issues fixed (#28475)

server/.golangci.yml

@@ -92,7 +92,6 @@ issues:
         channels/api4/license_test.go|\
         channels/api4/oauth_test.go|\
         channels/api4/outgoing_oauth_connection_test.go|\
-        channels/api4/permission.go|\
         channels/api4/plugin.go|\
         channels/api4/plugin_test.go|\
         channels/api4/post_test.go|\

server/channels/api4/permission.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 
 	"github.com/mattermost/mattermost/server/public/model"
+	"github.com/mattermost/mattermost/server/public/shared/mlog"
 )
 
 func (api *API) InitPermissions() {
@@ -25,5 +26,7 @@ func appendAncillaryPermissionsPost(c *Context, w http.ResponseWriter, r *http.R
 		c.SetJSONEncodingError(err)
 		return
 	}
-	w.Write(b)
+	if _, err := w.Write(b); err != nil {
+		c.Logger.Warn("Error while writing response", mlog.Err(err))
+	}
 }