Fix empty string comparison issues in the codebase (#16686)

Automatic Merge

model/access.go

@@ -38,11 +38,11 @@ type AccessResponse struct {
 // correctly.
 func (ad *AccessData) IsValid() *AppError {
 
-	if len(ad.ClientId) == 0 || len(ad.ClientId) > 26 {
+	if ad.ClientId == "" || len(ad.ClientId) > 26 {
 		return NewAppError("AccessData.IsValid", "model.access.is_valid.client_id.app_error", nil, "", http.StatusBadRequest)
 	}
 
-	if len(ad.UserId) == 0 || len(ad.UserId) > 26 {
+	if ad.UserId == "" || len(ad.UserId) > 26 {
 		return NewAppError("AccessData.IsValid", "model.access.is_valid.user_id.app_error", nil, "", http.StatusBadRequest)
 	}
 
@@ -54,7 +54,7 @@ func (ad *AccessData) IsValid() *AppError {
 		return NewAppError("AccessData.IsValid", "model.access.is_valid.refresh_token.app_error", nil, "", http.StatusBadRequest)
 	}
 
-	if len(ad.RedirectUri) == 0 || len(ad.RedirectUri) > 256 || !IsValidHttpUrl(ad.RedirectUri) {
+	if ad.RedirectUri == "" || len(ad.RedirectUri) > 256 || !IsValidHttpUrl(ad.RedirectUri) {
 		return NewAppError("AccessData.IsValid", "model.access.is_valid.redirect_uri.app_error", nil, "", http.StatusBadRequest)
 	}