propagate errors from longfi_send

Related to and depends on lora!1 (closed).

longfi-sys/build.rs

@@ -44,6 +44,7 @@ fn main() {
        .rustified_enum("RfEvent_t")
        .rustified_enum("QualityOfService_t")
        .rustified_enum("AntPinsMode_t")
+       .rustified_enum("SendError_t")
        .derive_copy(false)
        .derive_debug(false)
        .layout_tests(false)