Error: Content and Map of this Source is not available (only size() is supported)

[steverandy]

"gatsby-plugin-webpack-size": "2.0.1"
"gatsby": "3.0.4"

Got the following error when building production assets.

Error: Content and Map of this Source is not available (only size() is supported)
at SizeOnlySource._error (node_modules/webpack/node_modules/webpack-sources/lib/SizeOnlySource.js:16:10)
at SizeOnlySource.source (node_modules/webpack/node_modules/webpack-sources/lib/SizeOnlySource.js:26:14)
at node_modules/size-plugin/dist/size-plugin.cjs:2989:96
at Array.map (<anonymous>)
at SizePlugin.outputSizes (node_modules/size-plugin/dist/size-plugin.cjs:2989:48)

[cameronbraid]

GoogleChromeLabs/size-plugin#40