Wepback-merge or deepmerge for Webpack configuration?

I’d recommend sticking to webpack-merge.

deepmerge is not setup for webpack config objects.

When I tried to swap webpack-merge with deepmerge, I got many of these errors:

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema.
 - configuration[0].plugins[0] misses the property 'apply'.
   -> The run point of the plugin, required method.

Here are a couple discussions: