CLI: --stdio and --map together throw exception #3440
Description
It's often useful in a build process to be able to pipe the output of a command to another program (or to invoke a program as a subprocess that is being piped to/from).
cat foo.coffee | coffee --map --stdio doesn't work and errors out with the following:
TypeError: Cannot call method 'split' of null
at Object.exports.baseFileName (/root/lib/node_modules/coffee-script/lib/coffee-script/helpers.js:168:18)
at outputPath (/root/lib/node_modules/coffee-script/lib/coffee-script/command.js:430:24)
at writeJs (/root/lib/node_modules/coffee-script/lib/coffee-script/command.js:447:21)
at compileScript (/root/lib/node_modules/coffee-script/lib/coffee-script/command.js:225:18)
at Socket.<anonymous> (/root/lib/node_modules/coffee-script/lib/coffee-script/command.js:254:14)
at Socket.EventEmitter.emit (events.js:117:20)
at _stream_readable.js:920:16
at process._tickCallback (node.js:415:13)
coffee --print --map foo.coffee doesn't work, instead of the map it compiles and prints the compiled JS