--justlaunch argument fails trying to index dictionary with nil

[Timen]

Running any ios-deploy launch using the --justlaunch fails with the backtrace indicating nil is used to index a dictionary

Expected behavior

Successful start of app

Actual behavior.

Crashes with backtrace

*** First throw call stack:
(
	0   CoreFoundation                      0x00000001b31c5148 __exceptionPreprocess + 240
	1   libobjc.A.dylib                     0x00000001b2f0fe04 objc_exception_throw + 60
	2   CoreFoundation                      0x00000001b329716c -[__NSCFString characterAtIndex:].cold.1 + 0
	3   CoreFoundation                      0x00000001b329a6ec -[NSMutableDictionary __setObject:forKey:].cold.1 + 0
	4   CoreFoundation                      0x00000001b30fd458 -[__NSDictionaryM setObject:forKey:] + 0
	5   ios-deploy                          0x0000000102fcd618 get_connection_properties + 72
	6   ios-deploy                          0x0000000102fcdc80 create_remote_debug_server_socket + 32
	7   ios-deploy                          0x0000000102fce4b8 setup_lldb + 292
	8   ios-deploy                          0x0000000102fce724 launch_debugger_and_exit + 20
	9   ios-deploy                          0x0000000102fd55a4 handle_device + 1848
	10  MobileDevice                        0x0000000103b78bc4 _AMDDeviceAttachedCallbackv3 + 376
	11  MobileDevice                        0x0000000103ad3a20 _USBMuxCustomRunLoopSourcePerformCallback + 1196
	12  CoreFoundation                      0x00000001b3144f94 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28
	13  CoreFoundation                      0x00000001b3144ee0 __CFRunLoopDoSource0 + 208
	14  CoreFoundation                      0x00000001b3144be0 __CFRunLoopDoSources0 + 268
	15  CoreFoundation                      0x00000001b3143560 __CFRunLoopRun + 828
	16  CoreFoundation                      0x00000001b3142a84 CFRunLoopRunSpecific + 600
	17  CoreFoundation                      0x00000001b31cfc68 CFRunLoopRun + 64
	18  ios-deploy                          0x0000000102fd69ac main + 1960
	19  dyld                                0x000000010316508c start + 520
)

Steps to reproduce the problem

Install and launch a --bundle with the --justlaunch argument

[nisargjhaveri]

Sorry for this! Created #579 to fix it.