fixes #1633: error output when using `coffee -e`

lib/coffee-script/command.js

@@ -141,7 +141,7 @@
       CoffeeScript.emit('failure', err, task);
       if (CoffeeScript.listeners('failure').length) return;
       if (o.watch) return printLine(err.message);
-      printWarn(err.stack);
+      printWarn(err instanceof Error && err.stack || ("ERROR: " + err));
       return process.exit(1);
     }
   };

src/command.coffee

@@ -140,7 +140,7 @@ compileScript = (file, input, base) ->
     CoffeeScript.emit 'failure', err, task
     return if CoffeeScript.listeners('failure').length
     return printLine err.message if o.watch
-    printWarn err.stack
+    printWarn err instanceof Error and err.stack or "ERROR: #{err}"
     process.exit 1
 
 # Attach the appropriate listeners to compile scripts incoming over **stdin**,