DMT: seg fault when user exits application during 'step 1/3 Connecting to the migration cluster...' [CLC-442]

[sumnerib]

If the user presses 'Ctrl+c' while the front-end is trying to connect to the migration cluster ([1/3] Connecting to the migration cluster), the application will panic and print a stacktrace:

λ isaac-thinkpad hazelcast-enterprise-5.3.5-DM-SNAPSHOT-slim → ./bin/dmt --config migration.yaml start migration_config --yes

Hazelcast Data Migration Tool v5.3.0
(c) 2023 Hazelcast, Inc.

Selected data structures in the source cluster will be migrated to the target cluster.

Exiting the application does not affect the migration progress.
In order to cancel the migration, use the 'cancel' command.


panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xb4daa1]

goroutine 1 [running]:
github.com/hazelcast/hazelcast-go-client.(*ClientInternal).Client(...)
        github.com/hazelcast/[email protected]/client_internals.go:107
github.com/hazelcast/hazelcast-commandline-client/base/commands/migration.querySingleRow({0xe37ab0?, 0x146f460?}, 0xc00041f748?, {0xc0000523f0?, 0x2?})
        github.com/hazelcast/hazelcast-commandline-client/base/commands/migration/migration_stages.go:354 +0x21
github.com/hazelcast/hazelcast-commandline-client/base/commands/migration.maybePrintWarnings({0xe37ab0, 0x146f460}, {0xe3f1a0, 0xc0000da240}, 0x23?, {0xc000042630?, 0x22?})
        github.com/hazelcast/hazelcast-commandline-client/base/commands/migration/migration_stages.go:375 +0xce
github.com/hazelcast/hazelcast-commandline-client/base/commands/migration.StartCmd.Exec.func1()
        github.com/hazelcast/hazelcast-commandline-client/base/commands/migration/migration_start.go:68 +0x6e
github.com/hazelcast/hazelcast-commandline-client/base/commands/migration.StartCmd.Exec({}, {0xe37ab0, 0x146f460}, {0xe3f1a0, 0xc0000da240})
        github.com/hazelcast/hazelcast-commandline-client/base/commands/migration/migration_start.go:76 +0x7c6
github.com/hazelcast/hazelcast-commandline-client/clc/cmd.(*Main).createCommands.func1(0xc000005b00, {0xc000362880, 0x1, 0x4})
        github.com/hazelcast/hazelcast-commandline-client/clc/cmd/clc.go:348 +0x53f
github.com/spf13/cobra.(*Command).execute(0xc000005b00, {0xc000362840, 0x4, 0x4})
        github.com/spf13/[email protected]/command.go:940 +0x87c
github.com/spf13/cobra.(*Command).ExecuteC(0xc000004300)
        github.com/spf13/[email protected]/command.go:1068 +0x3a5
github.com/spf13/cobra.(*Command).Execute(...)
        github.com/spf13/[email protected]/command.go:992
github.com/spf13/cobra.(*Command).ExecuteContext(...)
        github.com/spf13/[email protected]/command.go:985
github.com/hazelcast/hazelcast-commandline-client/clc/cmd.(*Main).Execute(0xc0000da0c0, {0xe37ab0?, 0x146f460}, {0xc0000341f0, 0x5, 0x5})
        github.com/hazelcast/hazelcast-commandline-client/clc/cmd/clc.go:180 +0x234
main.main()
        github.com/hazelcast/hazelcast-commandline-client/cmd/clc/main.go:55 +0x3d0

To reproduce, run ./bin/dmt --config migration.yaml start migration_config --yes w/o any migration cluster running (so it won't connect) and then Ctrl+c the command.

Env:

Distributor ID: Ubuntu
Description:    Ubuntu 22.04.3 LTS
Release:        22.04
Codename:       jammy
kernel release: 6.2.0-36-generic

[github-actions]

Internal Jira issue: CLC-442