Call runningDSP.Get when runningDSP is not nil

[ffjlabo]

What this PR does:

I fixed to call runningDSP.Get when runningDSP is not nil.

Why we need it:

When first deploy, runningDSP is nil because previous running commit is not found.
So it led panic.

Which issue(s) this PR fixes:

Part of #4980

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[codecov]

Codecov Report

Attention: Patch coverage is 42.85714% with 4 lines in your changes missing coverage. Please review.

Project coverage is 26.45%. Comparing base (edcf430) to head (0f635be).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/app/pipedv1/controller/scheduler.go	42.85%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5541      +/-   ##
==========================================
+ Coverage   26.42%   26.45%   +0.02%     
==========================================
  Files         465      465              
  Lines       49858    49860       +2     
==========================================
+ Hits        13175    13188      +13     
+ Misses      35629    35618      -11     
  Partials     1054     1054              

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[Warashi]

LGTM

[t-kikuc]

like here? i got it

pipecd/pkg/app/piped/controller/scheduler.go

Lines 257 to 267 in edcf430

	if s.deployment.RunningCommitHash != "" {
	gp := *s.deployment.GitPath
	gp.ConfigFilename = s.deployment.RunningConfigFilename
	s.runningDSP = deploysource.NewProvider(
	filepath.Join(s.workingDir, "running-deploysource"),
	deploysource.NewGitSourceCloner(s.gitClient, repoCfg, "running", s.deployment.RunningCommitHash),
	gp,
	s.secretDecrypter,
	)
	}