Error: Cannot find module "webpack'?

This error typically occurs when the required module "webpack" is not installed or cannot be found in the current directory.

To resolve this issue, you can try the following steps:

Check if webpack is installed globally by running the following command:
```
webpack --version
```
If webpack is not installed, you can install it globally by running:
```
npm install -g webpack
```
If webpack is already installed globally, make sure the project's dependencies are installed by running:
```
npm install
```
If the issue persists, check if webpack is listed as a dependency in the project's package.json file. If not, you can install it locally by running the following command:
```
npm install --save-dev webpack
```
This will add webpack as a development dependency in the package.json file and install it in the node_modules folder.

If you still encounter the error after following these steps, try deleting the node_modules folder and reinstalling the dependencies using npm install. Sometimes, this can resolve conflicts or inconsistencies in the dependency installation.

Additionally, please ensure that you are running the commands in the correct directory and that the webpack configuration file (webpack.config.js) is present in the project root directory.