fix(gatsby): Multi-environment browserslist configs #35081
Merged
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Description
This PR fixes the logic in
getBrowsersList
to properly handle multi-environment Browserslist configs.More info available in #29943, though the root issue is the current logic always choosing
config.defaults
- with a multi-environment config, this may return[]
which (improperly) passes through the current logic check. This can have some pretty undesirable effects on parts of the build, including it currently breaking thehasES6ModuleSupport
helper and causing a build failure (see the reproduction repo).Fortunately, the fix is pretty simple: browserslist exposes a
loadConfig
function which has all of the necessary logic for picking the right config, including falling back todefaults
for the majority of cases. I haven't found a case where this breaks existing behavior, though please double check me on this!As an added bonus,
loadConfig
also respects theBROWSERSLIST_ENV
andBROWSERSLIST_CONFIG
environment variables which should make customizing build behavior a bit simpler.Related Issues
Fixes #29943