fix: mishandled error leading to nil dereference in metadata

[snakster]

What this PR does / why we need it:

This fixes a potential crash when trying to obtain the pull request metadata associated with a Github repository.

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?

no

[github-actions[bot]]

metric: time/op
CloudReadLines-4: old 1.02ms ± 4%: new 1.00ms ± 4%: delta: 0.00%
CloudReadLine-4: old 7.25ms ± 2%: new 7.24ms ± 1%: delta: 0.00%
ListFiles-4: old 52.1µs ± 1%: new 52.3µs ± 1%: delta: 0.43%
Generate-4: old 2.54s ± 2%: new 2.56s ± 1%: delta: 0.76%
GenerateRegex-4: old 1.72s ± 3%: new 1.74s ± 1%: delta: 1.05%
TokensForExpressionComplex-4: old 1.26ms ± 1%: new 1.26ms ± 0%: delta: -0.18%
TokensForExpressionPlainStringNoNewline-4: old 890ns ± 0%: new 887ns ± 1%: delta: -0.31%
TokensForExpressionStringWith100Newlines-4: old 21.7µs ± 0%: new 21.7µs ± 1%: delta: 0.00%
TokensForExpressionObjectWith100KeysWithNumberValues-4: old 1.45ms ± 0%: new 1.45ms ± 0%: delta: 0.14%
TokensForExpression-4: old 1.26ms ± 0%: new 1.26ms ± 0%: delta: 0.00%
PartialEvalComplex-4: old 433µs ± 1%: new 433µs ± 1%: delta: 0.00%
PartialEvalSmallString-4: old 3.60µs ± 0%: new 3.61µs ± 0%: delta: 0.00%
PartialEvalHugeString-4: old 1.87ms ± 0%: new 1.87ms ± 0%: delta: 0.00%
PartialEvalHugeInterpolatedString-4: old 4.92ms ± 1%: new 4.90ms ± 2%: delta: 0.00%
PartialEvalObject-4: old 21.6µs ± 0%: new 21.5µs ± 1%: delta: 0.00%
TmAllTrueLiteralList-4: old 6.26ms ± 0%: new 6.26ms ± 0%: delta: -0.12%
TmAllTrueFuncall-4: old 161µs ± 1%: new 160µs ± 0%: delta: -0.41%
TmAnyTrueLiteralList-4: old 148ms ± 1%: new 147ms ± 0%: delta: -0.48%
TmAnyTrueFuncall-4: old 161µs ± 1%: new 161µs ± 1%: delta: -0.24%
TmTernary-4: old 2.81µs ± 0%: new 2.83µs ± 0%: delta: 0.46%
TmTry-4: old 51.9µs ± 0%: new 52.0µs ± 1%: delta: 0.00%
metric: alloc/op
CloudReadLines-4: old 3.12MB ± 0%: new 3.12MB ± 0%: delta: -0.00%
CloudReadLine-4: old 3.37MB ± 0%: new 3.37MB ± 0%: delta: 0.00%
ListFiles-4: old 22.0kB ± 0%: new 22.0kB ± 0%: delta: 0.00%
Generate-4: old 2.32GB ± 0%: new 2.32GB ± 0%: delta: 0.00%
GenerateRegex-4: old 955MB ± 0%: new 956MB ± 0%: delta: 0.00%
TokensForExpressionComplex-4: old 412kB ± 0%: new 412kB ± 0%: delta: -0.00%
TokensForExpressionPlainStringNoNewline-4: old 592B ± 0%: new 592B ± 0%: delta: 0.00%
TokensForExpressionStringWith100Newlines-4: old 12.4kB ± 0%: new 12.4kB ± 0%: delta: 0.00%
TokensForExpressionObjectWith100KeysWithNumberValues-4: old 402kB ± 0%: new 402kB ± 0%: delta: 0.00%
TokensForExpression-4: old 412kB ± 0%: new 412kB ± 0%: delta: 0.00%
PartialEvalComplex-4: old 356kB ± 0%: new 356kB ± 0%: delta: 0.00%
PartialEvalSmallString-4: old 1.74kB ± 0%: new 1.74kB ± 0%: delta: 0.00%
PartialEvalHugeString-4: old 166kB ± 0%: new 166kB ± 0%: delta: 0.00%
PartialEvalHugeInterpolatedString-4: old 4.38MB ± 0%: new 4.38MB ± 0%: delta: 0.00%
PartialEvalObject-4: old 20.4kB ± 0%: new 20.4kB ± 0%: delta: 0.00%
TmAllTrueLiteralList-4: old 1.74MB ± 0%: new 1.74MB ± 0%: delta: 0.00%
TmAllTrueFuncall-4: old 45.5kB ± 0%: new 45.5kB ± 0%: delta: -0.00%
TmAnyTrueLiteralList-4: old 37.9MB ± 0%: new 37.9MB ± 0%: delta: 0.00%
TmAnyTrueFuncall-4: old 45.6kB ± 0%: new 45.6kB ± 0%: delta: 0.00%
TmTernary-4: old 1.20kB ± 0%: new 1.20kB ± 0%: delta: 0.00%
TmTry-4: old 11.2kB ± 0%: new 11.2kB ± 0%: delta: 0.00%
metric: allocs/op
CloudReadLines-4: old 5.54k ± 0%: new 5.54k ± 0%: delta: 0.00%
CloudReadLine-4: old 60.0k ± 0%: new 60.0k ± 0%: delta: 0.00%
ListFiles-4: old 321 ± 0%: new 321 ± 0%: delta: 0.00%
Generate-4: old 25.9M ± 0%: new 25.9M ± 0%: delta: 0.00%
GenerateRegex-4: old 18.6M ± 0%: new 18.6M ± 0%: delta: 0.00%
TokensForExpressionComplex-4: old 4.93k ± 0%: new 4.93k ± 0%: delta: 0.00%
TokensForExpressionPlainStringNoNewline-4: old 21.0 ± 0%: new 21.0 ± 0%: delta: 0.00%
TokensForExpressionStringWith100Newlines-4: old 228 ± 0%: new 228 ± 0%: delta: 0.00%
TokensForExpressionObjectWith100KeysWithNumberValues-4: old 3.29k ± 0%: new 3.29k ± 0%: delta: 0.00%
TokensForExpression-4: old 4.93k ± 0%: new 4.93k ± 0%: delta: 0.00%
PartialEvalComplex-4: old 2.86k ± 0%: new 2.86k ± 0%: delta: 0.00%
PartialEvalSmallString-4: old 23.0 ± 0%: new 23.0 ± 0%: delta: 0.00%
PartialEvalHugeString-4: old 35.0 ± 0%: new 35.0 ± 0%: delta: 0.00%
PartialEvalHugeInterpolatedString-4: old 23.1k ± 0%: new 23.1k ± 0%: delta: 0.00%
PartialEvalObject-4: old 125 ± 0%: new 125 ± 0%: delta: 0.00%
TmAllTrueLiteralList-4: old 13.6k ± 0%: new 13.6k ± 0%: delta: 0.00%
TmAllTrueFuncall-4: old 460 ± 0%: new 460 ± 0%: delta: 0.00%
TmAnyTrueLiteralList-4: old 252k ± 0%: new 252k ± 0%: delta: 0.00%
TmAnyTrueFuncall-4: old 462 ± 0%: new 462 ± 0%: delta: 0.00%
TmTernary-4: old 28.0 ± 0%: new 28.0 ± 0%: delta: 0.00%
TmTry-4: old 147 ± 0%: new 147 ± 0%: delta: 0.00%

[i4ki]

cases to be checked:

• local commit is not pushed, then getPR... will return an error
• commit is pushed but not associated with any PR
• commit is pushed but associated with many PRs
• any other?

@snakster did you validate these cases?

[snakster]

@i4ki

• local commit is not pushed, then getPR... will return an error: ✅

  s1 % terramate run --sync-deployment -- echo "deploying" 
  2024-05-07T17:44:31+02:00 WRN failed to retrieve commit information from GitHub API error="GET https://api.github.com/repos/snakster/metadata-test/commits/43f671846957491c579ed5f7b4d41a106445cb3c: 422 No commit found for SHA: 43f671846957491c579ed5f7b4d41a106445cb3c []" github_repository=snakster/metadata-test head_commit=43f671846957491c579ed5f7b4d41a106445cb3c normalized_repository=github.com/snakster/metadata-test
  2024-05-07T17:44:31+02:00 WRN failed to retrieve pull requests associated with HEAD error="GET https://api.github.com/repos/snakster/metadata-test/commits/43f671846957491c579ed5f7b4d41a106445cb3c/pulls?per_page=1: 422 No commit found for SHA: 43f671846957491c579ed5f7b4d41a106445cb3c []" commit=43f671846957491c579ed5f7b4d41a106445cb3c github_repository=snakster/metadata-test
  terramate: Entering stack in /s1
  terramate: Executing command "echo deploying"
  deploying

• commit is pushed but not associated with any PR: ✅

  s1 % terramate run --sync-deployment -- echo "deploying"
  terramate: Entering stack in /s1
  terramate: Executing command "echo deploying"
  deploying

• commit is pushed but associated with many PRs: ✅

  s1 % terramate run --sync-deployment -- echo "deploying"                                                            
  terramate: Entering stack in /s1
  terramate: Executing command "echo deploying"
  deploying