Error when upgrading to gatsby-plugin-postcss 3.0.4

[mor10]

Standard setup working fine with gatsby-plugin-postcss v2.3.13. When upgrading to v3.0.4, I get the following error when running gatsby develop:

error Generating development JavaScript bundle failed
postcss-preset-env is missing from your plugins, you need to use it in order for css-customs-loader to work properly.

Reverting back to v2.3.13 resolves the issue.

Note: gatsby-plugin-postcss v3.0.4 works fine on its own. The conflict is caused by gatsby-css-customs.

[samblackk]

Also experiencing this exactly how the issue reported described.