Update license.go (handled error) (#28410)

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/channels/api4/license.go

@@ -45,7 +45,9 @@ func getClientLicense(c *Context, w http.ResponseWriter, r *http.Request) {
 		clientLicense = c.App.Srv().GetSanitizedClientLicense()
 	}
 
-	w.Write([]byte(model.MapToJSON(clientLicense)))
+	if _, err := w.Write([]byte(model.MapToJSON(clientLicense))); err != nil {
+		c.Logger.Warn("Error while writing response", mlog.Err(err))
+	}
 }
 
 func addLicense(c *Context, w http.ResponseWriter, r *http.Request) {
@@ -93,7 +95,10 @@ func addLicense(c *Context, w http.ResponseWriter, r *http.Request) {
 	defer file.Close()
 
 	buf := bytes.NewBuffer(nil)
-	io.Copy(buf, file)
+	if _, err := io.Copy(buf, file); err != nil {
+		c.Err = model.NewAppError("addLicense", "api.license.add_license.copy.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
+		return
+	}
 
 	licenseBytes := buf.Bytes()
 	license, appErr := utils.LicenseValidator.LicenseFromBytes(licenseBytes)
@@ -137,7 +142,11 @@ func addLicense(c *Context, w http.ResponseWriter, r *http.Request) {
 
 	if c.App.Channels().License().IsCloud() {
 		// If cloud, invalidate the caches when a new license is loaded
-		defer c.App.Srv().Cloud.HandleLicenseChange()
+		defer func() {
+			if err := c.App.Srv().Cloud.HandleLicenseChange(); err != nil {
+				c.Logger.Warn("Error while handling license change", mlog.Err(err))
+			}
+		}()
 	}
 
 	auditRec.Success()
@@ -258,5 +267,8 @@ func getPrevTrialLicense(c *Context, w http.ResponseWriter, r *http.Request) {
 		clientLicense = utils.GetSanitizedClientLicense(utils.GetClientLicense(license))
 	}
 
-	w.Write([]byte(model.MapToJSON(clientLicense)))
+	w.Header().Set("Content-Type", "application/json")
+	if _, err := w.Write([]byte(model.MapToJSON(clientLicense))); err != nil {
+		c.Logger.Warn("Error while writing response", mlog.Err(err))
+	}
 }