Add more linters to improve code readability (#19989)

Add nakedret, unconvert, wastedassign, stylecheck and nolintlint linters to improve code readability

- nakedret - https://github.com/alexkohler/nakedret - nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.
- unconvert - https://github.com/mdempsky/unconvert - Remove unnecessary type conversions
- wastedassign - https://github.com/sanposhiho/wastedassign -  wastedassign finds wasted assignment statements.
- notlintlint -  Reports ill-formed or insufficient nolint directives
- stylecheck - https://staticcheck.io/docs/checks/#ST - keep style consistent
  - excluded: [ST1003 - Poorly chosen identifier](https://staticcheck.io/docs/checks/#ST1003) and [ST1005 - Incorrectly formatted error string](https://staticcheck.io/docs/checks/#ST1005)

models/issues/issue.go

@@ -223,7 +223,7 @@ func (issue *Issue) GetPullRequest() (pr *PullRequest, err error) {
 		return nil, err
 	}
 	pr.Issue = issue
-	return
+	return pr, err
 }
 
 // LoadLabels loads labels
@@ -255,7 +255,7 @@ func (issue *Issue) loadPoster(ctx context.Context) (err error) {
 			return
 		}
 	}
-	return
+	return err
 }
 
 func (issue *Issue) loadPullRequest(ctx context.Context) (err error) {
@@ -311,7 +311,7 @@ func (issue *Issue) loadReactions(ctx context.Context) (err error) {
 		return err
 	}
 	// Load reaction user data
-	if _, err := ReactionList(reactions).LoadUsers(ctx, issue.Repo); err != nil {
+	if _, err := reactions.LoadUsers(ctx, issue.Repo); err != nil {
 		return err
 	}
 
@@ -2110,7 +2110,7 @@ func updateIssueClosedNum(ctx context.Context, issue *Issue) (err error) {
 	} else {
 		err = repo_model.StatsCorrectNumClosed(ctx, issue.RepoID, false, "num_closed_issues")
 	}
-	return
+	return err
 }
 
 // FindAndUpdateIssueMentions finds users mentioned in the given content string, and saves them in the database.
@@ -2123,7 +2123,7 @@ func FindAndUpdateIssueMentions(ctx context.Context, issue *Issue, doer *user_mo
 	if err = UpdateIssueMentions(ctx, issue.ID, mentions); err != nil {
 		return nil, fmt.Errorf("UpdateIssueMentions [%d]: %v", issue.ID, err)
 	}
-	return
+	return mentions, err
 }
 
 // ResolveIssueMentionsByVisibility returns the users mentioned in an issue, removing those that
@@ -2257,7 +2257,7 @@ func ResolveIssueMentionsByVisibility(ctx context.Context, issue *Issue, doer *u
 		users = append(users, user)
 	}
 
-	return
+	return users, err
 }
 
 // UpdateIssuesMigrationsByType updates all migrated repositories' issues from gitServiceType to replace originalAuthorID to posterID
@@ -2380,7 +2380,7 @@ func DeleteIssuesByRepoID(ctx context.Context, repoID int64) (attachmentPaths []
 		return
 	}
 
-	return
+	return attachmentPaths, err
 }
 
 // RemapExternalUser ExternalUserRemappable interface