title: Adding a leaflet Extension to React-Leaflet
body: <p>I'm trying to use &quot;Leaflet.Heightgraph&quot; on my React app. For this React app, I've used &quot;React-Leaflet&quot;.</p>
  <p>My issue is that I cannot use the required initialization for Leaflet.Heightgraph - which is L.control.Heightgraph().
  Doing so returns the following error:</p>
  <pre><code>Uncaught TypeError: leaflet__WEBPACK_IMPORTED_MODULE_7___default.a.control.heightgraph is not a function
      at CompMap (CompMap.jsx:289:1)
      at renderWithHooks (react-dom.development.js:14985:1)
      at mountIndeterminateComponent (react-dom.development.js:17811:1)
      at beginWork (react-dom.development.js:19049:1)
      at HTMLUnknownElement.callCallback (react-dom.development.js:3945:1)
      at Object.invokeGuardedCallbackDev (react-dom.development.js:3994:1)
      at invokeGuardedCallback (react-dom.development.js:4056:1)
      at beginWork$1 (react-dom.development.js:23964:1)
      at performUnitOfWork (react-dom.development.js:22779:1)
      at workLoopSync (react-dom.development.js:22707:1)
      at renderRootSync (react-dom.development.js:22670:1)
      at performSyncWorkOnRoot (react-dom.development.js:22293:1)
      at scheduleUpdateOnFiber (react-dom.development.js:21881:1)
      at updateContainer (react-dom.development.js:25482:1)
      at react-dom.development.js:26021:1
      at unbatchedUpdates (react-dom.development.js:22431:1)
      at legacyRenderSubtreeIntoContainer (react-dom.development.js:26020:1)
      at Object.render (react-dom.development.js:26103:1)
      at Module../src/index.js (index.js:14:1)
      at __webpack_require__ (bootstrap:784:1)
      at fn (bootstrap:150:1)
      at Object.1 (serviceWorker.js:164:1)
      at __webpack_require__ (bootstrap:784:1)
      at checkDeferredModules (bootstrap:45:1)
      at Array.webpackJsonpCallback [as push] (bootstrap:32:1)
      at main.chunk.js:1:65
  </code></pre>
  <p>I'm pretty sure I've added all the needed imports.
  If relevant, I'm using L.icon without any issues. And using this import <code>import L from &quot;leaflet&quot;; import LH from &quot;leaflet.heightgraph&quot;;</code></p>