1.21.0 includes a breaking change

[yesmeck]

• Rollup Version: 1.21.0
• Operating System (or Browser): Chrome
• Node Version: 12

How Do We Reproduce?

#3080 introduced asset.type breaks all plugins which generate asset using asset.isAsset.

Expected Behavior

Minor version should backward compatibility。

Actual Behavior

It's breaks many plugins, like rollup-plugin-postcss

[lukastaegert]

I see. Admittedly, these plugins were using an unofficial API, so technically it is only a breaking change in something we never promised to keep compatible; the proper way to emit assets is to use the file emission API, not mutate the bundle object.

I admit though that the file emission API only got powerful enough recently to support arbitrary asset emission, so I guess we will need to add a "fix" to keep supporting this pattern for the 1.x releases, especially considering that important plugins currently depend on it.

[lukastaegert]

Fix at #3105

[slavafomin]

@lukastaegert thank you for fixing it so quickly. When should we expect the new release (1.21.1)?

[lukastaegert]

Released now