client/webserver/site: babel build error

[chappjc]

$   npm --version
6.14.3
$   npm i
...
added 1351 packages from 637 contributors and audited 15266 packages in 14.755s
...
$   npm run build

> dexclient@1.0.0 build /home/jon/github/decred/dcrdex/client/webserver/site
> webpack --config webpack/prod.js --progress --colors

Hash: c1f84cc5149d4000c376
Version: webpack 4.41.5
Time: 1154ms
Built at: 03/25/2020 10:30:57 AM
 2 assets
Entrypoint app = entry.js entry.js.map
[0] ./src/index.js 3.32 KiB {0} [built] [failed] [1 error]

ERROR in ./src/index.js
Module build failed (from ./node_modules/babel-loader/lib/index.js):
Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: No "exports" main resolved in /home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/helper-compilation-targets/package.json
    at applyExports (internal/modules/cjs/loader.js:524:9)
    at resolveExports (internal/modules/cjs/loader.js:541:12)
    at Function.Module._findPath (internal/modules/cjs/loader.js:661:22)
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:963:27)
    at Function.Module._load (internal/modules/cjs/loader.js:859:27)
    at Module.require (internal/modules/cjs/loader.js:1036:19)
    at require (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/webpack-cli/node_modules/v8-compile-cache/v8-compile-cache.js:161:20)
    at Object.<anonymous> (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/preset-env/lib/debug.js:8:33)
    at Module._compile (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/webpack-cli/node_modules/v8-compile-cache/v8-compile-cache.js:192:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1167:10)
    at Module.load (internal/modules/cjs/loader.js:996:32)
    at Function.Module._load (internal/modules/cjs/loader.js:896:14)
    at Module.require (internal/modules/cjs/loader.js:1036:19)
    at require (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/webpack-cli/node_modules/v8-compile-cache/v8-compile-cache.js:161:20)
    at Object.<anonymous> (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/preset-env/lib/index.js:11:14)
    at Module._compile (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/webpack-cli/node_modules/v8-compile-cache/v8-compile-cache.js:192:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1167:10)
    at Module.load (internal/modules/cjs/loader.js:996:32)
    at Function.Module._load (internal/modules/cjs/loader.js:896:14)
    at Module.require (internal/modules/cjs/loader.js:1036:19)
    at require (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/webpack-cli/node_modules/v8-compile-cache/v8-compile-cache.js:161:20)
    at requireModule (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/core/lib/config/files/plugins.js:165:12)
    at loadPreset (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/core/lib/config/files/plugins.js:83:17)
    at createDescriptor (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/core/lib/config/config-descriptors.js:154:9)
    at /home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/core/lib/config/config-descriptors.js:109:50
    at Array.map (<anonymous>)
    at createDescriptors (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/core/lib/config/config-descriptors.js:109:29)
    at createPresetDescriptors (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/core/lib/config/config-descriptors.js:101:10)
    at /home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/core/lib/config/config-descriptors.js:58:104
    at cachedFunction (/home/jon/github/decred/dcrdex/client/webserver/site/node_modules/@babel/core/lib/config/caching.js:62:27)
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! dexclient@1.0.0 build: `webpack --config webpack/prod.js --progress --colors`
npm ERR! Exit status 2
npm ERR! 
npm ERR! Failed at the dexclient@1.0.0 build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/jon/.npm/_logs/2020-03-25T15_30_57_807Z-debug.log

It seems to be related to this node change: nodejs/node#31625

However, this is not really reproducible since we do not have package-lock.json checked in, hence the versions are not locked down. On my end, this was fixable by one of:

• rm -rf node_modules package-lock.json && npm i OR
• npm up
  Both of these installed newer versions of the dependencies than the minimum versions listed in package.lock. Before trying the above I had:

$   npm out
Package                    Current  Wanted  Latest  Location
@babel/core                  7.8.3   7.9.0   7.9.0  dexclient
@babel/preset-env            7.8.3   7.9.0   7.9.0  dexclient
babel-eslint                10.0.3  10.1.0  10.1.0  dexclient
babel-loader                 8.0.6   8.1.0   8.1.0  dexclient
eslint-config-standard      14.1.0  14.1.1  14.1.1  dexclient
eslint-plugin-import        2.20.0  2.20.1  2.20.1  dexclient
eslint-plugin-react         7.18.0  7.19.0  7.19.0  dexclient
stylelint                   12.0.1  12.0.1  13.2.1  dexclient
stylelint-config-standard   19.0.0  19.0.0  20.0.0  dexclient
stylelint-webpack-plugin     1.2.1   1.2.3   1.2.3  dexclient
terser-webpack-plugin        2.3.2   2.3.5   2.3.5  dexclient
webpack                     4.41.5  4.42.1  4.42.1  dexclient
webpack-bundle-analyzer      3.6.0   3.6.1   3.6.1  dexclient
webpack-cli                 3.3.10  3.3.11  3.3.11  dexclient
webpack-dev-server          3.10.1  3.10.3  3.10.3  dexclient

I briefly searched the babel core and babel loader release notes, but didn't see anything. In any case, we should bump the minimum babel deps.