Use settings from observable in chart

local-storage/index.js

@@ -1,13 +1,22 @@
 import { AsyncStorage } from 'react-native'
 import Observable from 'obv'
+import config from '../config'
 
 export const tempScaleObservable = Observable()
-getTempScale()
+setTempScaleInitially()
 
-async function getTempScale() {
+async function setTempScaleInitially() {
   const result = await AsyncStorage.getItem('tempScale')
-  if (!result) return result
-  tempScaleObservable.set(JSON.parse(result))
+  let value
+  if (result) {
+    value = JSON.parse(result)
+  } else {
+    value = {
+      min: config.temperatureScale.defaultLow,
+      max: config.temperatureScale.defaultHigh
+    }
+  }
+  tempScaleObservable.set(value)
 }
 
 export async function saveTempScale(scale) {