trace_api_plugin reports block trace missing when http-max-response-time-ms limit is reached

[heifner]

{"code":404,"message":"Trace API: block trace missing","error":{"code":0,"name":"","what":"","details":[]}}

https://github.com/AntelopeIO/leap/blob/v4.0.4/plugins/trace_api_plugin/abi_data_handler.cpp#L40 Calls except_handler when yield() throw exception and returns {}. The except_handler is setup to https://github.com/AntelopeIO/leap/blob/v4.0.4/plugins/trace_api_plugin/trace_api_plugin.cpp#L204 only log the error. This means a small http-max-response-time-ms causes trace_api_plugin to indicate it could not find the block rather than a deadline exception was hit.