[bugfix] Rework MultiError to wrap + unwrap errors properly (#2057)

* rework multierror a bit

* test multierror

6 files changed, 58 insertions, 36 deletions

diff --git a/internal/db/bundb/account.go b/internal/db/bundb/account.go
index 6a47418b7..83b3c13f5 100644
--- a/internal/db/bundb/account.go
+++ b/internal/db/bundb/account.go
@@ -20,7 +20,6 @@ package bundb
 import (
 	"context"
 	"errors"
-	"fmt"
 	"strings"
 	"time"
 
@@ -255,7 +254,7 @@ func (a *accountDB) getAccount(ctx context.Context, lookup string, dbQuery func(
 func (a *accountDB) PopulateAccount(ctx context.Context, account *gtsmodel.Account) error {
 	var (
 		err  error
-		errs = make(gtserror.MultiError, 0, 3)
+		errs = gtserror.NewMultiError(3)
 	)
 
 	if account.AvatarMediaAttachment == nil && account.AvatarMediaAttachmentID != "" {
@@ -265,7 +264,7 @@ func (a *accountDB) PopulateAccount(ctx context.Context, account *gtsmodel.Accou
 			account.AvatarMediaAttachmentID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating account avatar: %w", err))
+			errs.Appendf("error populating account avatar: %w", err)
 		}
 	}
 
@@ -276,7 +275,7 @@ func (a *accountDB) PopulateAccount(ctx context.Context, account *gtsmodel.Accou
 			account.HeaderMediaAttachmentID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating account header: %w", err))
+			errs.Appendf("error populating account header: %w", err)
 		}
 	}
 
@@ -287,11 +286,15 @@ func (a *accountDB) PopulateAccount(ctx context.Context, account *gtsmodel.Accou
 			account.EmojiIDs,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating account emojis: %w", err))
+			errs.Appendf("error populating account emojis: %w", err)
 		}
 	}
 
-	return errs.Combine()
+	if err := errs.Combine(); err != nil {
+		return gtserror.Newf("%w", err)
+	}
+
+	return nil
 }
 
 func (a *accountDB) PutAccount(ctx context.Context, account *gtsmodel.Account) error {
diff --git a/internal/db/bundb/instance.go b/internal/db/bundb/instance.go
index 48332c731..6657072fd 100644
--- a/internal/db/bundb/instance.go
+++ b/internal/db/bundb/instance.go
@@ -173,7 +173,7 @@ func (i *instanceDB) getInstance(ctx context.Context, lookup string, dbQuery fun
 func (i *instanceDB) populateInstance(ctx context.Context, instance *gtsmodel.Instance) error {
 	var (
 		err  error
-		errs = make(gtserror.MultiError, 0, 2)
+		errs = gtserror.NewMultiError(2)
 	)
 
 	if instance.DomainBlockID != "" && instance.DomainBlock == nil {
@@ -183,7 +183,7 @@ func (i *instanceDB) populateInstance(ctx context.Context, instance *gtsmodel.In
 			instance.Domain,
 		)
 		if err != nil {
-			errs.Append(gtserror.Newf("error populating instance domain block: %w", err))
+			errs.Appendf("error populating instance domain block: %w", err)
 		}
 	}
 
@@ -194,11 +194,15 @@ func (i *instanceDB) populateInstance(ctx context.Context, instance *gtsmodel.In
 			instance.ContactAccountID,
 		)
 		if err != nil {
-			errs.Append(gtserror.Newf("error populating instance contact account: %w", err))
+			errs.Appendf("error populating instance contact account: %w", err)
 		}
 	}
 
-	return errs.Combine()
+	if err := errs.Combine(); err != nil {
+		return gtserror.Newf("%w", err)
+	}
+
+	return nil
 }
 
 func (i *instanceDB) PutInstance(ctx context.Context, instance *gtsmodel.Instance) error {
diff --git a/internal/db/bundb/list.go b/internal/db/bundb/list.go
index 70faf837a..ad970f539 100644
--- a/internal/db/bundb/list.go
+++ b/internal/db/bundb/list.go
@@ -117,7 +117,7 @@ func (l *listDB) GetListsForAccountID(ctx context.Context, accountID string) ([]
 func (l *listDB) PopulateList(ctx context.Context, list *gtsmodel.List) error {
 	var (
 		err  error
-		errs = make(gtserror.MultiError, 0, 2)
+		errs = gtserror.NewMultiError(2)
 	)
 
 	if list.Account == nil {
@@ -127,7 +127,7 @@ func (l *listDB) PopulateList(ctx context.Context, list *gtsmodel.List) error {
 			list.AccountID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating list account: %w", err))
+			errs.Appendf("error populating list account: %w", err)
 		}
 	}
 
@@ -139,11 +139,15 @@ func (l *listDB) PopulateList(ctx context.Context, list *gtsmodel.List) error {
 			"", "", "", 0,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating list entries: %w", err))
+			errs.Appendf("error populating list entries: %w", err)
 		}
 	}
 
-	return errs.Combine()
+	if err := errs.Combine(); err != nil {
+		return gtserror.Newf("%w", err)
+	}
+
+	return nil
 }
 
 func (l *listDB) PutList(ctx context.Context, list *gtsmodel.List) error {
diff --git a/internal/db/bundb/relationship_follow.go b/internal/db/bundb/relationship_follow.go
index 3b0597612..e22ed30de 100644
--- a/internal/db/bundb/relationship_follow.go
+++ b/internal/db/bundb/relationship_follow.go
@@ -160,7 +160,7 @@ func (r *relationshipDB) getFollow(ctx context.Context, lookup string, dbQuery f
 func (r *relationshipDB) PopulateFollow(ctx context.Context, follow *gtsmodel.Follow) error {
 	var (
 		err  error
-		errs = make(gtserror.MultiError, 0, 2)
+		errs = gtserror.NewMultiError(2)
 	)
 
 	if follow.Account == nil {
@@ -170,7 +170,7 @@ func (r *relationshipDB) PopulateFollow(ctx context.Context, follow *gtsmodel.Fo
 			follow.AccountID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating follow account: %w", err))
+			errs.Appendf("error populating follow account: %w", err)
 		}
 	}
 
@@ -181,11 +181,15 @@ func (r *relationshipDB) PopulateFollow(ctx context.Context, follow *gtsmodel.Fo
 			follow.TargetAccountID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating follow target account: %w", err))
+			errs.Appendf("error populating follow target account: %w", err)
 		}
 	}
 
-	return errs.Combine()
+	if err := errs.Combine(); err != nil {
+		return gtserror.Newf("%w", err)
+	}
+
+	return nil
 }
 
 func (r *relationshipDB) PutFollow(ctx context.Context, follow *gtsmodel.Follow) error {
diff --git a/internal/db/bundb/status.go b/internal/db/bundb/status.go
index c34074dd6..25b773dfa 100644
--- a/internal/db/bundb/status.go
+++ b/internal/db/bundb/status.go
@@ -22,7 +22,6 @@ import (
 	"context"
 	"database/sql"
 	"errors"
-	"fmt"
 	"time"
 
 	"github.com/superseriousbusiness/gotosocial/internal/db"
@@ -129,7 +128,7 @@ func (s *statusDB) getStatus(ctx context.Context, lookup string, dbQuery func(*g
 func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status) error {
 	var (
 		err  error
-		errs = make(gtserror.MultiError, 0, 9)
+		errs = gtserror.NewMultiError(9)
 	)
 
 	if status.Account == nil {
@@ -139,7 +138,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 			status.AccountID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status author: %w", err))
+			errs.Appendf("error populating status author: %w", err)
 		}
 	}
 
@@ -150,7 +149,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 			status.InReplyToID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status parent: %w", err))
+			errs.Appendf("error populating status parent: %w", err)
 		}
 	}
 
@@ -162,7 +161,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 				status.InReplyToID,
 			)
 			if err != nil {
-				errs.Append(fmt.Errorf("error populating status parent: %w", err))
+				errs.Appendf("error populating status parent: %w", err)
 			}
 		}
 
@@ -173,7 +172,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 				status.InReplyToAccountID,
 			)
 			if err != nil {
-				errs.Append(fmt.Errorf("error populating status parent author: %w", err))
+				errs.Appendf("error populating status parent author: %w", err)
 			}
 		}
 	}
@@ -186,7 +185,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 				status.BoostOfID,
 			)
 			if err != nil {
-				errs.Append(fmt.Errorf("error populating status boost: %w", err))
+				errs.Appendf("error populating status boost: %w", err)
 			}
 		}
 
@@ -197,7 +196,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 				status.BoostOfAccountID,
 			)
 			if err != nil {
-				errs.Append(fmt.Errorf("error populating status boost author: %w", err))
+				errs.Appendf("error populating status boost author: %w", err)
 			}
 		}
 	}
@@ -209,7 +208,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 			status.AttachmentIDs,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status attachments: %w", err))
+			errs.Appendf("error populating status attachments: %w", err)
 		}
 	}
 
@@ -220,7 +219,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 			status.TagIDs,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status tags: %w", err))
+			errs.Appendf("error populating status tags: %w", err)
 		}
 	}
 
@@ -231,7 +230,7 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 			status.MentionIDs,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status mentions: %w", err))
+			errs.Appendf("error populating status mentions: %w", err)
 		}
 	}
 
@@ -242,11 +241,15 @@ func (s *statusDB) PopulateStatus(ctx context.Context, status *gtsmodel.Status)
 			status.EmojiIDs,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status emojis: %w", err))
+			errs.Appendf("error populating status emojis: %w", err)
 		}
 	}
 
-	return errs.Combine()
+	if err := errs.Combine(); err != nil {
+		return gtserror.Newf("%w", err)
+	}
+
+	return nil
 }
 
 func (s *statusDB) PutStatus(ctx context.Context, status *gtsmodel.Status) error {
diff --git a/internal/db/bundb/statusfave.go b/internal/db/bundb/statusfave.go
index a8d1cd0d1..7aff543fd 100644
--- a/internal/db/bundb/statusfave.go
+++ b/internal/db/bundb/statusfave.go
@@ -149,7 +149,7 @@ func (s *statusFaveDB) GetStatusFavesForStatus(ctx context.Context, statusID str
 func (s *statusFaveDB) PopulateStatusFave(ctx context.Context, statusFave *gtsmodel.StatusFave) error {
 	var (
 		err  error
-		errs = make(gtserror.MultiError, 0, 3)
+		errs = gtserror.NewMultiError(3)
 	)
 
 	if statusFave.Account == nil {
@@ -159,7 +159,7 @@ func (s *statusFaveDB) PopulateStatusFave(ctx context.Context, statusFave *gtsmo
 			statusFave.AccountID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status fave author: %w", err))
+			errs.Appendf("error populating status fave author: %w", err)
 		}
 	}
 
@@ -170,7 +170,7 @@ func (s *statusFaveDB) PopulateStatusFave(ctx context.Context, statusFave *gtsmo
 			statusFave.TargetAccountID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status fave target account: %w", err))
+			errs.Appendf("error populating status fave target account: %w", err)
 		}
 	}
 
@@ -181,11 +181,15 @@ func (s *statusFaveDB) PopulateStatusFave(ctx context.Context, statusFave *gtsmo
 			statusFave.StatusID,
 		)
 		if err != nil {
-			errs.Append(fmt.Errorf("error populating status fave status: %w", err))
+			errs.Appendf("error populating status fave status: %w", err)
 		}
 	}
 
-	return errs.Combine()
+	if err := errs.Combine(); err != nil {
+		return gtserror.Newf("%w", err)
+	}
+
+	return nil
 }
 
 func (s *statusFaveDB) PutStatusFave(ctx context.Context, fave *gtsmodel.StatusFave) error {