Fix if there is no data returned

citizenair/R/appdata.R

@@ -144,10 +144,17 @@ CitizenAir <- R6::R6Class("CitizenAir",
                             df <- sensorweb4R::getData(x, timespan = timespan)
                             df <- as.data.frame(df)
                             df$date <- as.Date(df$time)
-                            df$phenomena_id <- sensorweb4R::id(sensorweb4R::phenomenon(x))
-                            df$phenomena <- self$getPhenomenaLabel(df$phenomena_id)
-                            df$timeseries_id <- sensorweb4R::id(x)
-                            df$timeseries_label <- sensorweb4R::label(x)
+                            if(nrow(df) > 0){
+                              df$phenomena_id <- sensorweb4R::id(sensorweb4R::phenomenon(x))
+                              df$phenomena <- self$getPhenomenaLabel(df$phenomena_id)
+                              df$timeseries_id <- sensorweb4R::id(x)
+                              df$timeseries_label <- sensorweb4R::label(x)
+                            }else{
+                              df$phenomena_id <- character()
+                              df$phenomena <- self$getPhenomenaLabel(df$phenomena_id)
+                              df$timeseries_id <- character()
+                              df$timeseries_label <- character()
+                            }
                             df$type <- rep("official", nrow(df))
                             result[[i]] <- df[, c("type", "timeseries_id", "timeseries_label", "phenomena_id", "phenomena", "time", "date", "value")]
                           }