$ cat dbus-error.scm
(use dbus posix)

(define (make-service-context service)
  (make-context bus: system-bus
                service: 'net.connman
                interface: 'net.connman.Service
                path: (make-pathname "/net/connman/service"
                                     service)))

(let ((c (make-service-context "foo")))
  (call c "GetProperties" ))


$ csi -s dbus-error.scm

Error: (call) (org.freedesktop.DBus.Error.ServiceUnknown): The name net.connman was not provided by any .service files

        Call history:

        <syntax>          [make-service-context] (##core#begin (make-context bus: system-bus service: (quote net.connman) interface: (quote net.connm......
        <syntax>          [make-service-context] (make-context bus: system-bus service: (quote net.connman) interface: (quote net.connman.Service) pa......
        <syntax>          [make-service-context] (quote net.connman)
        <syntax>          [make-service-context] (##core#quote net.connman)
        <syntax>          [make-service-context] (quote net.connman.Service)
        <syntax>          [make-service-context] (##core#quote net.connman.Service)
        <syntax>          [make-service-context] (make-pathname "/net/connman/service" service)
        <syntax>          (let ((c (make-service-context "foo"))) (call c "GetProperties"))
        <syntax>          (##core#let ((c (make-service-context "foo"))) (call c "GetProperties"))
        <syntax>          (##core#begin (call c "GetProperties"))
        <syntax>          (call c "GetProperties")
        <syntax>          (make-service-context "foo")
        <eval>    (make-service-context "foo")
        <eval>    [make-service-context] (make-context bus: system-bus service: (quote net.connman) interface: (quote net.connman.Service) pa......
        <eval>    [make-service-context] (make-pathname "/net/connman/service" service)
        <eval>    (call c "GetProperties")      <--