How to access provider members within a component in Ionic 4 - ionic-framework

Question

I have a provider having a method getWeather() and I want to call it from home component. When I am trying to call getWeather() from home component I am getting error in console like: ERROR TypeError: Cannot read property 'getWeather' of undefined
weather.ts
import { Http } from '#angular/http';
import { Injectable } from '#angular/core';
import "rxjs/add/operator/map";
#Injectable()
export class WeatherProvider {
constructor(public http: Http) {
console.log('Hello WeatherProvider Provider: ');
}
getWeather() {
return this.http.get('https://samples.openweathermap.org/data/2.5/forecast?q=London,us&appid=b6907d289e10d714a6e88b30761fae22').map(res=>res.json());
}
}
home.ts
import { Component } from '#angular/core';
import { NavController } from 'ionic-angular';
import { WeatherProvider } from "../../providers/weather/weather";
//import { HttpModule } from "#angular/http";
#Component({
selector: 'page-home',
templateUrl: 'home.html'
})
export class HomePage {
weather:any;
constructor(public navCtrl: NavController, private wp:WeatherProvider) {
}
ionViewWillEnter() {
this.weather.getWeather().subscribe(weather=>{
console.log(weather)
})
}
}

Answer 1

The error is gone after restarting the ionic dev server. I don't know why the ionic is behaving like this.