Electron Build ERROR at //v8/BUILD.gn:503:30: Undefined identifier

Question

I'm trying to build electron source using command -

gn gen out/Testing --args="import(\"//electron/build/args/testing.gn\")"

Keep getting this error -

ERROR at //v8/BUILD.gn:503:30: Undefined identifier
if (!is_component_build && is_electron_build) {
                           ^----------------
See //BUILD.gn:219:7: which caused the file to be included.
  "//v8:gn_all",
  ^------------

I couldn't figure out what I'm missing. I checked again, all the instructions and requirements, all good. Looks like it is pointing to is_electron_build. I don't know where this is coming from.

I'm following this https://www.electronjs.org/docs/development/build-instructions-gn