closes#1391
uglify-js is an optional dependency and should be treated as such.
This commit gracefully handles MODULE_NOT_FOUND errors while loading
uglify.
- Check for existing uglify-js (and load uglify-js) only if minification
was activated
- Use "require.resolve" to check if uglify exists. Otherwise, a missing
dependency of uglify-js would cause the same behavior as missing
uglify-js. (Only a warning, no error)
- The code to load and run uglify is put into a single for readability
purposes
- Tests use a mockup Module._resolveFilename to simulate the missing module.
This function is used by both "require" and "require.resolve", so both
are mocked equally.
(cherry picked from commit d5caa56)
Nils Knappmeier
79309659e1