Merge pull request #8334 from theotherjimmy/error-missing-payload

mbed dm: Check for missing payload and give a better error message

tools/device_management.py

@@ -82,6 +82,9 @@ def wrap_payload(func):
             app_name = config.name or basename(abspath(sources[0]))
             payload_name = join(options.build, generate_update_filename(app_name, config.target))
             options.payload = open(payload_name, "rb")
+        if not options.payload:
+            LOG.error("No Payload specified. Please use \"-t\" and \"-m\" or \"-p\" to specify a payload ")
+            exit(1)
         return func(options)
     return inner