Agent might crash during installation of signing pkgs

https://testresults.qt.io/coin/api/results/qt/qtbase/7b2238e68b95eaf678b0705c657982aae2bd5c26/MacOSMacOS_12x86_64MacOSMacOS_12x86_64Clangqtci-macos-12-x86_64-105-e65d6cSccache_UseConfigure_WarningsAreErrors/fd06743cc49ade3a0d8dc5d9d133484d0918700f/build_1678978745/log.txt.gz 

agent:2022/10/20 02:23:15 agent.go:239: Recovered from panic: runtime error: invalid memory address or nil pointer dereference
agent:2022/10/20 02:23:15 agent.go:240: goroutine 6 [running]:
runtime/debug.Stack()
/var/lib/coin/go18/src/runtime/debug/stack.go:24 +0x65
main.executeInstructionsGoroutine.func2()
/var/lib/coin/tqtc-coin-ci/src/agent/agent.go:240 +0xb3
panic({0x14c48a0, 0x18c7130})
/var/lib/coin/go18/src/runtime/panic.go:838 +0x207
github.com/pkg/sftp.(*Client).nextID(...)
/var/lib/coin/tqtc-coin-ci/pkg/mod/github.com/pkg/sftp@v1.13.5/client.go:264
github.com/pkg/sftp.(*Client).open(0x0, {0x15523ac, 0x24}, 0x1)
/var/lib/coin/tqtc-coin-ci/pkg/mod/github.com/pkg/sftp@v1.13.5/client.go:581 +0x30
github.com/pkg/sftp.(*Client).Open(0xc00009a000?, {0x15523ac?, 0xc00012e2a0?})
/var/lib/coin/tqtc-coin-ci/pkg/mod/github.com/pkg/sftp@v1.13.5/client.go:570 +0x25
main.(*agentHandler).installSecretsSSHKeys(0xc000111d30?, {0xc00002a0d0, 0x9})
/var/lib/coin/tqtc-coin-ci/src/agent/process_helper.go:123 +0xa7
main.executeInstructionsGoroutine(0xc00009a000, 0xc000202120, 0xc000093798?)
/var/lib/coin/tqtc-coin-ci/src/agent/agent.go:343 +0xe85
created by main.(*agentHandler).ExecuteInstructions
/var/lib/coin/tqtc-coin-ci/src/agent/agent.go:121 +0xaa