improve errors for invalid module.json files
improve errors for invalid module.json files

ARMmbed/yotta,theotherjimmy/yotta,eyeye/yotta,bridadan/yotta,autopulated/yotta,ntoll/yotta,stevenewey/yotta,BlackstoneEngineering/yotta,eyeye/yotta,stevenewey/yotta,bridadan/yotta,BlackstoneEngineering/yotta,ARMmbed/yotta,autopulated/yotta,theotherjimmy/yotta,ntoll/yotta,iriark01/yotta,iriark01/yotta