In G4KLX DStarGateway and F4FXL DStarGateway before 7b75de6, dstarCallsignToAPRS in APRSUtils.cpp has an integer underflow via an empty RS-MS1A sender field.
Integer Underflow (Wrap or Wraparound) The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.