Not Able to Use $http or Vue.http

Here are some steps and adjustments to ensure Vue Resource is set up correctly:

1. Ensure Vue Resource is Installed Correctly

Double-check your `package.json` to ensure that `vue-resource` is listed as a dependency. Run `npm install` or `yarn install` to make sure all dependencies are installed.

2. Import and Use Vue Resource Properly

When using Vue Resource, you need to import it and then use it with Vue. Based on your setup, it looks like you’re using `require` for this, which should work, but it’s often clearer to use ES6 imports.

Update your `main.js` to the following:

import Vue from 'vue';
import VueResource from 'vue-resource';
import VueMaterial from 'vue-material';
import App from './App.vue';

Vue.use(VueMaterial);
Vue.use(VueResource);
new Vue({
    el: '#app',
    render: h => h(App),
    mounted() {
        console.log(this.$http); // Ensure $http is available
    },
});

3. Check `this` Context in `mounted` Hook

In Vue, `this` inside the `mounted` hook should refer to the Vue instance, so `this.$http` should be available. If it’s not, you might need to verify your environment and Vue setup.

4. Verify Vue Resource API Calls

Ensure you’re using the API calls correctly. Here’s a quick example of how you might make a GET request using Vue Resource:

export default {
    mounted() {
        this.$http.get('https://api.example.com/data').then(
            response => {
                // Success callback
                console.log(response.body);
            },
            response => {
                // Error callback
                console.error(response);
            },
        );
    },
};

5. Double-Check Vue Version Compatibility

You are using `vue@2.2.1` and `vue-resource@1.3.1`. Ensure that these versions are compatible. Generally, `vue-resource` should work with Vue 2.x, but it’s good to verify that you have compatible versions.