Merge branch 'fix/error-when-invalid-branch-for-new-pipeline-used' into 'master'

Fix error when using invalid branch name when creating a new pipeline

## What does this MR do?

This MR fixes `500` error when creating a new pipeline though user interface ("Run pipeline")

## Are there points in the code the reviewer needs to double check?

Is this a good approach to catch those exceptions on `Repository` level?

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- Tests
  - [x] Added for this feature/bug

## What are the relevant issue numbers?

Closes #23982

See merge request !7324

2 files changed, 9 insertions, 7 deletions

diff --git a/app/controllers/projects/pipelines_controller.rb b/app/controllers/projects/pipelines_controller.rb
index 371cc3787fb..533af80aee0 100644
--- a/app/controllers/projects/pipelines_controller.rb
+++ b/app/controllers/projects/pipelines_controller.rb
@@ -18,7 +18,9 @@ class Projects::PipelinesController < Projects::ApplicationController
   end
 
   def create
-    @pipeline = Ci::CreatePipelineService.new(project, current_user, create_params).execute(ignore_skip_ci: true, save_on_errors: false)
+    @pipeline = Ci::CreatePipelineService
+      .new(project, current_user, create_params)
+      .execute(ignore_skip_ci: true, save_on_errors: false)
     unless @pipeline.persisted?
       render 'new'
       return
diff --git a/app/models/repository.rb b/app/models/repository.rb
index 7d06ce1e85b..fe991904601 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -84,15 +84,17 @@ class Repository
 
   def commit(ref = 'HEAD')
     return nil unless exists?
+
     commit =
       if ref.is_a?(Gitlab::Git::Commit)
         ref
       else
         Gitlab::Git::Commit.find(raw_repository, ref)
       end
+
     commit = ::Commit.new(commit, @project) if commit
     commit
-  rescue Rugged::OdbError
+  rescue Rugged::OdbError, Rugged::TreeError
     nil
   end
 
@@ -232,6 +234,8 @@ class Repository
 
   def ref_exists?(ref)
     rugged.references.exist?(ref)
+  rescue Rugged::ReferenceError
+    false
   end
 
   def update_ref!(name, newrev, oldrev)
@@ -270,11 +274,7 @@ class Repository
   end
 
   def kept_around?(sha)
-    begin
-      ref_exists?(keep_around_ref_name(sha))
-    rescue Rugged::ReferenceError
-      false
-    end
+    ref_exists?(keep_around_ref_name(sha))
   end
 
   def tag_names