axios: DefaultAdapter returns unknown/undefined by default

Describe the bug The Default Adapter returns with out being set if the if/elseif isn’t met. This means an axios call (through AWS Amplify API) in nextJS getInitialProps throws because “Adapter is not a function”

To Reproduce Make a next js project with amplify and init with api. GraphQL uses axios to make the calls. Tracing the stack shows that the axios defaults module does not set the adapter.

Expected behavior The adapter should be set.

Environment:

• Axios Version 0.19.0
• OS: MacOs
• Browser Chrome
• Additional Library Versions Next 9.1.1

Additional context/Screenshots

function getDefaultAdapter() {
  var adapter;
  // Only Node.JS has a process variable that is of [[Class]] process
  if (typeof process !== 'undefined' && Object.prototype.toString.call(process) === '[object process]') {
    // For node use HTTP adapter
    adapter = require('./adapters/http');
  } else if (typeof XMLHttpRequest !== 'undefined') {
    // For browsers use XHR adapter
    adapter = require('./adapters/xhr');
  }
  return adapter;
}

This is the method. The “Object.prototype.toString.call(process) === ‘[object process]’” is false because the process in nextJS is “‘[object Object]’”

This isn’t just an issue with nextJS. An if/elseif should never, imo, fall-through and return a variable that hasn’t been set. Throw from there or set a default in an else block.