servod: provide a more informative error on usb disconnect

Currently servod will fail with regex-unmatched on a USB disconnect.
However, this makes it hard to distinguish from an ec/cr50 command
failure, or an ec3po hang. So we'll print a distinctive error in this case.

TEST=error when ccd is umplugged.

Change-Id: Ifa941d736897d61170f341226b255ab76eddfa5c
Signed-off-by: Nick Sanders <>
Commit-Ready: ChromeOS CL Exonerator Bot <>
Reviewed-by: Mary Ruthven <>
2 files changed