This string add operator problem was associated to Galileo firmware version 0x0000030e / 782. You can find the firmware version by using cat /sys/firmware/board_data/flash_version from the Galileo Linux command prompt.
This issues appears to have been corrected in Galileo firmware 0x01000000 / 1.0.0. Just grab the latest version of the IDE with the 1.0.0 FW build from https://communities.intel.com/docs/DOC-22226 and update the Galileo Firmware (Ardinuo IDE -> "Help" -> "Firmware Update").
--Matt Royer