build error

[bwanaaa]

% ./mkapp internal/modules/cjs/loader.js:888 throw err; ^

Error: Cannot find module 'nw-builder' Require stack:

• /private/tmp/appbuild.js at Function.Module._resolveFilename (internal/modules/cjs/loader.js:885:15) at Function.Module._load (internal/modules/cjs/loader.js:730:27) at Module.require (internal/modules/cjs/loader.js:957:19) at require (internal/modules/cjs/helpers.js:88:18) at Object. (/private/tmp/appbuild.js:1:17) at Module._compile (internal/modules/cjs/loader.js:1068:30) at Object.Module._extensions..js (internal/modules/cjs/loader.js:1097:10) at Module.load (internal/modules/cjs/loader.js:933:32) at Function.Module._load (internal/modules/cjs/loader.js:774:14) at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12) { code: 'MODULE_NOT_FOUND', requireStack: [ '/private/tmp/appbuild.js' ] } ERROR: Failed to package MeshCommander.app

what/where is appbuild.js?