jfrog cli panics when no default config is defined

Describe the bug

When no default config is defined ("isDefault": false) in jfrog-cli.conf.v6, cli panics

Current behavior

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x14a pc=0xcae14ba]

goroutine 1 [running]:
github.com/jfrog/jfrog-cli-core/v2/utils/config.excludeRefreshableTokensFromDetails(...)
    github.com/jfrog/jfrog-cli-core/v2@v2.52.0/utils/config/config.go:82
github.com/jfrog/jfrog-cli-core/v2/utils/config.GetSpecificConfig({0x0, 0x0}, 0x1, 0x1)
    github.com/jfrog/jfrog-cli-core/v2@v2.52.0/utils/config/config.go:61 +0x27a
github.com/jfrog/jfrog-cli-core/v2/common/commands.(*CurlCommand).GetServerDetails(0xc000112140)
    github.com/jfrog/jfrog-cli-core/v2@v2.52.0/common/commands/curl.go:140 +0x178
github.com/jfrog/jfrog-cli/artifactory.newRtCurlCommand(0x1?)
    github.com/jfrog/jfrog-cli/artifactory/cli.go:1831 +0x18b
github.com/jfrog/jfrog-cli/artifactory.curlCmd(0xc0001302c0)
    github.com/jfrog/jfrog-cli/artifactory/cli.go:1821 +0x5d
github.com/urfave/cli.HandleAction({0xd078680?, 0xd20a150?}, 0x4?)
    github.com/urfave/cli@v1.22.15/app.go:524 +0x50
github.com/urfave/cli.Command.Run({{0xcd70eca, 0x4}, {0x0, 0x0}, {0xc00033dd70, 0x1, 0x1}, {0xce0d1c0, 0x41}, {0xcdd8fc9, ...}, ...}, ...)
    github.com/urfave/cli@v1.22.15/command.go:175 +0x685
github.com/urfave/cli.(*App).RunAsSubcommand(0xc000584380, 0xc00037fce0)
    github.com/urfave/cli@v1.22.15/app.go:405 +0xdfb
github.com/urfave/cli.Command.startApp({{0xcd6ff4d, 0x2}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0xcda6a34, 0x15}, {0x0, ...}, ...}, ...)
    github.com/urfave/cli@v1.22.15/command.go:380 +0xb1e
github.com/urfave/cli.Command.Run({{0xcd6ff4d, 0x2}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0xcda6a34, 0x15}, {0x0, ...}, ...}, ...)
    github.com/urfave/cli@v1.22.15/command.go:103 +0x7c5
github.com/urfave/cli.(*App).Run(0xc0001d4700, {0xc000036040, 0x4, 0x4})
    github.com/urfave/cli@v1.22.15/app.go:277 +0xb3b
main.execMain()
    github.com/jfrog/jfrog-cli/main.go:148 +0x4b5
main.main()
    github.com/jfrog/jfrog-cli/main.go:84 +0x1c

Reproduction steps

add new config without "isDefault": true, e.g. jfrog-cli.conf.v6:

{
"servers": [
{
  "url": "https://**********/",
  "artifactoryUrl": "https://**********/artifactory/",
  "distributionUrl": "https://**********/distribution/",
  "xrayUrl": "https://**********/xray/",
  "missionControlUrl": "https://**********/mc/",
  "pipelinesUrl": "https://**********/pipelines/",
  "user": "username",
  "accessToken": "TOKEN",
  "refreshToken": "*********",
  "serverId": "my-server",
  "isDefault": false,
  "webLogin": true
}
],
"version": "6"
}

run jf rt curl api/system/ping

Expected behavior

cli should not to panic, expected error message

JFrog CLI version

jf version 2.56.1

Operating system type and version

macOS

JFrog Artifactory version

No response

JFrog Xray version