Introduction to 'react-leaflet core cjs pane.js:7 error'

If you are working with react-leaflet, you might encounter the error message "react-leaflet core cjs pane.js:7 error". This error is related to the usage of the pane property in React Leaflet's Pane component.

Understanding the Pane component in React Leaflet

The Pane component in react-leaflet is used to group layers together and manage their rendering order. It allows you to create custom layers and overlays, and control their interaction with the map.

When using the Pane component, you can specify the pane property to set the name of the pane that the layer will be added to. If the specified pane does not exist, it will be created automatically.

The 'react-leaflet core cjs pane.js:7 error'

The error message "react-leaflet core cjs pane.js:7 error" is related to the usage of the pane property in the Pane component. The error occurs when the pane property is not defined, and the default value (context.pane) is not available. This can happen when you are trying to render a custom layer or overlay that has not been added to a pane yet.

To fix this error, you need to make sure that the pane property is defined before rendering the layer. You can either set the pane property to a valid pane name, or use the default value (context.pane) by making sure that the layer is added to a parent component that has a valid pane property.

Example of fixing the 'react-leaflet core cjs pane.js:7 error'

Here is an example of how to fix the "react-leaflet core cjs pane.js:7 error". Assume that you are trying to render a custom layer called MyLayer:

import { Pane } from 'react-leaflet';

function MyLayer(props) {
  const { pane } = props; // assume that pane is not defined

  return (
    <Pane name={pane}> // this will cause the error
      // ...
    </Pane>
  );
}

To fix the error, you can either set the pane property to a valid pane name:

function MyLayer(props) {
  const { pane } = props;

  return (
    <Pane name={pane || 'myPane'}>
      // ...
    </Pane>
  );
}

Or make sure that the layer is added to a parent component that has a valid pane property:

import { Pane } from 'react-leaflet';

function MyParentComponent() {
  return (
    <Pane name="myPane">
      <MyLayer />
    </Pane>
  );
}

function MyLayer(props, context) {
  const { pane } = props;

  return (
    <Pane name={pane ?? context.pane}>
      // ...
    </Pane>
  );
}

By following these steps, you can fix the "react-leaflet core cjs pane.js:7 error" and render custom layers and overlays in react-leaflet.