Conkeror fails to start, and an error is dumped to the console.  Happened
to a user with XULRunner 7 on Arch.  Stack trace is as follows:

Error initializing.
NS_ERROR_XPC_GS_RETURNED_FAILURE: Component returned failure code: 0x80570016
(NS_ERROR_XPC_GS_RETURNED_FAILURE) [nsIJSCID.getService]
null()@chrome://conkeror/content/services.js:22
load1()@file:///usr/share/conkeror/components/application.js:102
null()@file:///usr/share/conkeror/components/application.js:177
null()@file:///usr/share/conkeror/components/application.js:278
null()@chrome://conkeror/content/conkeror.js:20
load1()@file:///usr/share/conkeror/components/application.js:102
null()@file:///usr/share/conkeror/components/application.js:177
null()@file:///usr/share/conkeror/components/application.js:278
application()@file:///usr/share/conkeror/components/application.js:35
null()@resource://gre/modules/XPCOMUtils.jsm:301
null()@file:///usr/share/conkeror/components/command-line.js:20
Console error: [JavaScript Error: "conkeror.handle_command_line is not a function" {file:
"file:///usr/share/conkeror/components/command-line.js" line: 23}]
  Category: XPConnect JavaScript

This error seems to be caused by the same thing that underlies issue376.  This one is harder to solve,
though, because in that case, the component in question was optional, and so could safely be not loaded
during startup, while here, the component (command-line) is required during startup.