gistfile1.txt

var gulp = require('gulp');
var browserify = require('browserify');

gulp.task('watchify', function() {
  gulp.watch('client.js', function(file) {
    browserify()
      .add(file);
  });
});

gistfile2.txt

[12:20:07] Using gulpfile ~/Code/gee-el/gulpfile.js
[12:20:07] Starting 'watchify'...
[12:20:07] Finished 'watchify' after 11 ms
path.js:8
    throw new TypeError('Path must be a string. Received ' +
    ^

TypeError: Path must be a string. Received undefined
    at assertPath (path.js:8:11)
    at Object.posix.resolve (path.js:426:5)
    at Deps._transform (/Users/cbryan/Code/gee-el/node_modules/module-deps/index.js:90:32)
    at Deps.Transform._read (/Users/cbryan/Code/gee-el/node_modules/readable-stream/lib/_stream_transform.js:172:10)
    at Deps.Transform._write (/Users/cbryan/Code/gee-el/node_modules/readable-stream/lib/_stream_transform.js:160:12)
    at Labeled.Pipeline._write (/Users/cbryan/Code/gee-el/node_modules/stream-splicer/index.js:70:22)
    at doWrite (/Users/cbryan/Code/gee-el/node_modules/readable-stream/lib/_stream_writable.js:333:12)
    at writeOrBuffer (/Users/cbryan/Code/gee-el/node_modules/readable-stream/lib/_stream_writable.js:319:5)
    at Labeled.Writable.write (/Users/cbryan/Code/gee-el/node_modules/readable-stream/lib/_stream_writable.js:246:11)
    at Labeled.ondata (/Users/cbryan/Code/gee-el/node_modules/readable-stream/lib/_stream_readable.js:581:20)