feat: load hermes-parser conditionally when hermes is enabled
#855
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The package `hermes-parser` has a lot of JS that goes unused in web platforms, this leads to increased bundle time.
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Summary: - There are [general performance improvements](#855) from conditionally importing Hermes. - `metro-hermes-compiler` is doing some gnarly error handling that makes debugging Metro quite painful. If you get an error in Metro after `metro-hermes-compiler` has been loaded, it will look something like: <img width="1900" alt="Screen Shot 2022-08-23 at 1 28 43 PM" src="https://user-images.githubusercontent.com/9664363/186146899-57817ce9-9cef-439b-a421-98b9aec216fb.png"> This PR doesn't fix the core issue but it does alleviate Metro web and JSC development where Hermes is not used: ``` TypeError [ERR_INVALID_ARG_TYPE]: The "to" argument must be of type string. Received undefined at new NodeError (node:internal/errors:371:5) at validateString (node:internal/validators:119:11) at Object.relative (node:path:1192:5) at MetroTerminalReporter._getBundleStatusMessage (/Users/evanbacon/Documents/GitHub/expo/packages/expo/cli/build/src/start/server/metro/MetroTerminalReporter.js:44:41) at /Users/evanbacon/Documents/GitHub/expo/node_modules/metro/src/lib/TerminalReporter.js:393:14 at Array.map (<anonymous>) at MetroTerminalReporter._getStatusMessage (/Users/evanbacon/Documents/GitHub/expo/node_modules/metro/src/lib/TerminalReporter.js:392:8) at MetroTerminalReporter.update (/Users/evanbacon/Documents/GitHub/expo/node_modules/metro/src/lib/TerminalReporter.js:423:31) at Object.update (/Users/evanbacon/Documents/GitHub/expo/packages/expo/cli/build/src/start/server/metro/instantiateMetro.js:21:30) at Server.requestProcessor [as _processBundleRequest] (/Users/evanbacon/Documents/GitHub/metro/packages/metro/src/Server.js:653:22) at async Server._processRequest (/Users/evanbacon/Documents/GitHub/metro/packages/metro/src/Server.js:504:9) ``` Pull Request resolved: #856 Test Plan: Throw an error somewhere in the resolver, Metro will throw a reasonable Node error instead of the Hermes error. Reviewed By: motiz88 Differential Revision: D38940701 Pulled By: cipolleschi fbshipit-source-id: 472fa775c5ae6a39acb6d0195f926a1013a4b425
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Summary
The package
hermes-parserhas a lot of JS that goes unused in web platforms, this leads to increased bundle time.Test plan
Before
After