Zapier CLI zipping projects fails on nullish coalescing assignment modern syntax browserify

After upgrading to Zapier platform v13 (Node 16) and targeting Node 16 in Babel, zapier push fails at "Zipping projects and dependencies", the browserify-based bundler cannot parse modern syntax like nullish coalescing assignment (??=) or private class fields/methods (#privateMethod), erroring on the # symbol.

Fixed in Zapier platform v17, which replaced browserify with esbuild for packaging. Upgrade the CLI/core to v17 and modern syntax (??=, private fields/methods) bundles cleanly. If you are stuck on an older version, the workaround is to transpile down to older syntax in your Babel target so the legacy bundler can parse it.

Source: https://github.com/zapier/zapier-platform/issues/614

Source: https://github.com/zapier/zapier-platform/issues/614