Check for nil ptr proxy-url value in troubleshoot util

[nephomaniac]

What type of PR is this?

bug

What this PR does / Why we need it?

Fixes nil pointer deference seg fault during the troubleshoot util
Adds notice in the troubleshoot util for missing config file if not found at the expected path.

Which Jira/Github issue(s) does this PR fix?

Resolves #

Special notes for your reviewer

This should address the following error when "proxy-url" value is not set in the current configuration file/path, and not provided as an environment var.

[BP]➜ ~/rh_sandbox/backplane-cli/ git:(main) ✗ ./ocm-backplane config troubleshoot
[V] backplane-cli configuration path: /Users/maclark/.config/backplane/config.json
WARN[0001] No proxy configuration available. This may result in failing commands as backplane-api is only available from select networks. 
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x0 pc=0x1036af5ec]

goroutine 1 [running]:
github.com/openshift/backplane-cli/cmd/ocm-backplane/config.(*troubleshootOptions).checkBPCli(0x0?)
	/Users/maclark/rh_sandbox/backplane-cli/cmd/ocm-backplane/config/troubleshoot.go:73 +0x20c
github.com/openshift/backplane-cli/cmd/ocm-backplane/config.(*troubleshootOptions).run(0x1059c0968, 0x43995fd100000000?, {0x14000605b68?, 0x0?, 0x0?})
	/Users/maclark/rh_sandbox/backplane-cli/cmd/ocm-backplane/config/troubleshoot.go:122 +0x20
github.com/spf13/cobra.(*Command).execute(0x14000485808, {0x1059c0968, 0x0, 0x0})
	/Users/maclark/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:983 +0x840
github.com/spf13/cobra.(*Command).ExecuteC(0x105881980)
	/Users/maclark/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:1115 +0x344
github.com/spf13/cobra.(*Command).Execute(...)
	/Users/maclark/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:1039
main.Execute()
	/Users/maclark/rh_sandbox/backplane-cli/cmd/ocm-backplane/root.go:56 +0x24
main.main()
	/Users/maclark/rh_sandbox/backplane-cli/cmd/ocm-backplane/main.go:20 +0x1c

Pre-checks (if applicable)

• Ran unit tests locally
• Validated the changes in a cluster
• Included documentation changes with PR

[nephomaniac]

/retest

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 16.66667% with 5 lines in your changes missing coverage. Please review.

Project coverage is 45.89%. Comparing base (c21ada9) to head (0370068).
Report is 14 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #436      +/-   ##
==========================================
+ Coverage   44.51%   45.89%   +1.37%     
==========================================
  Files          63       63              
  Lines        5284     5731     +447     
==========================================
+ Hits         2352     2630     +278     
- Misses       2615     2767     +152     
- Partials      317      334      +17     

Files	Coverage Δ
cmd/ocm-backplane/config/troubleshoot.go	63.29% <16.66%> (-4.28%)	⬇️

... and 4 files with indirect coverage changes

[feichashao]

/lgtm
/approve

[feichashao]

@nephomaniac Thank you for fixing this!

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: feichashao, nephomaniac

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[openshift-ci]

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