[#1502] Use zap.Error for logging errors

Use `zap.Error` instead of `zap.String` for logging errors: change all expressions like
`zap.String("error", err.Error())` or `zap.String("err", err.Error())` to `zap.Error(err)`.
Leave similar expressions with other messages unchanged, for example,
`zap.String("last_error", lastErr.Error())` or `zap.String("reason", ctx.Err().Error())`.

This change was made by applying the following patch:
```diff
@@
var err expression
@@
-zap.String("error", err.Error())
+zap.Error(err)

@@
var err expression
@@
-zap.String("err", err.Error())
+zap.Error(err)
```

Signed-off-by: Aleksey Savchuk <a.savchuk@yadro.com>

pkg/local_object_storage/blobstor/blobovniczatree/delete.go

@@ -82,7 +82,7 @@ func (b *Blobovniczas) Delete(ctx context.Context, prm common.DeletePrm) (res co
 			if !client.IsErrObjectNotFound(err) {
 				b.log.Debug(ctx, logs.BlobovniczatreeCouldNotRemoveObjectFromLevel,
 					zap.String("level", p),
-					zap.String("error", err.Error()),
+					zap.Error(err),
 					zap.String("trace_id", tracingPkg.GetTraceID(ctx)),
 				)
 			}

pkg/local_object_storage/blobstor/blobovniczatree/exists.go

@@ -57,7 +57,7 @@ func (b *Blobovniczas) Exists(ctx context.Context, prm common.ExistsPrm) (common
 			if !client.IsErrObjectNotFound(err) {
 				b.log.Debug(ctx, logs.BlobovniczatreeCouldNotGetObjectFromLevel,
 					zap.String("level", p),
-					zap.String("error", err.Error()),
+					zap.Error(err),
 					zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
 			}
 		}

pkg/local_object_storage/blobstor/blobovniczatree/get.go

@@ -69,7 +69,7 @@ func (b *Blobovniczas) Get(ctx context.Context, prm common.GetPrm) (res common.G
 			if !client.IsErrObjectNotFound(err) {
 				b.log.Debug(ctx, logs.BlobovniczatreeCouldNotGetObjectFromLevel,
 					zap.String("level", p),
-					zap.String("error", err.Error()),
+					zap.Error(err),
 					zap.String("trace_id", tracingPkg.GetTraceID(ctx)),
 				)
 			}

pkg/local_object_storage/blobstor/blobovniczatree/get_range.go

@@ -71,7 +71,7 @@ func (b *Blobovniczas) GetRange(ctx context.Context, prm common.GetRangePrm) (re
 			if !outOfBounds && !client.IsErrObjectNotFound(err) {
 				b.log.Debug(ctx, logs.BlobovniczatreeCouldNotGetObjectFromLevel,
 					zap.String("level", p),
-					zap.String("error", err.Error()),
+					zap.Error(err),
 					zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
 			}
 			if outOfBounds {

pkg/local_object_storage/blobstor/blobovniczatree/iterate.go

@@ -44,7 +44,7 @@ func (b *Blobovniczas) Iterate(ctx context.Context, prm common.IteratePrm) (comm
 				if prm.IgnoreErrors {
 					b.log.Warn(ctx, logs.BlobstorErrorOccurredDuringTheIteration,
 						zap.Stringer("address", elem.Address()),
-						zap.String("err", err.Error()),
+						zap.Error(err),
 						zap.String("storage_id", p),
 						zap.String("root_path", b.rootPath))
 					return nil
@@ -77,7 +77,7 @@ func (b *Blobovniczas) iterateBlobovniczas(ctx context.Context, ignoreErrors boo
 		if err != nil {
 			if ignoreErrors {
 				b.log.Warn(ctx, logs.BlobstorErrorOccurredDuringTheIteration,
-					zap.String("err", err.Error()),
+					zap.Error(err),
 					zap.String("storage_id", p),
 					zap.String("root_path", b.rootPath))
 				return false, nil

pkg/local_object_storage/blobstor/blobovniczatree/manager.go

@@ -97,7 +97,7 @@ func (b *sharedDB) Close(ctx context.Context) {
 		if err := b.blcza.Close(ctx); err != nil {
 			b.log.Error(ctx, logs.BlobovniczatreeCouldNotCloseBlobovnicza,
 				zap.String("id", b.path),
-				zap.String("error", err.Error()),
+				zap.Error(err),
 			)
 		}
 		b.blcza = nil
@@ -125,7 +125,7 @@ func (b *sharedDB) CloseAndRemoveFile(ctx context.Context) error {
 	if err := b.blcza.Close(ctx); err != nil {
 		b.log.Error(ctx, logs.BlobovniczatreeCouldNotCloseBlobovnicza,
 			zap.String("id", b.path),
-			zap.String("error", err.Error()),
+			zap.Error(err),
 		)
 		return fmt.Errorf("failed to close blobovnicza (path = %s): %w", b.path, err)
 	}

pkg/local_object_storage/blobstor/blobovniczatree/put.go

@@ -83,7 +83,7 @@ func (i *putIterator) iterate(ctx context.Context, lvlPath string) (bool, error)
 			i.B.reportError(ctx, logs.BlobovniczatreeCouldNotGetActiveBlobovnicza, err)
 		} else {
 			i.B.log.Debug(ctx, logs.BlobovniczatreeCouldNotGetActiveBlobovnicza,
-				zap.String("error", err.Error()),
+				zap.Error(err),
 				zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
 		}
 
@@ -106,7 +106,7 @@ func (i *putIterator) iterate(ctx context.Context, lvlPath string) (bool, error)
 		} else {
 			i.B.log.Debug(ctx, logs.BlobovniczatreeCouldNotPutObjectToActiveBlobovnicza,
 				zap.String("path", active.SystemPath()),
-				zap.String("error", err.Error()),
+				zap.Error(err),
 				zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
 		}
 		if errors.Is(err, blobovnicza.ErrNoSpace) {

pkg/local_object_storage/blobstor/control.go

@@ -74,7 +74,7 @@ func (b *BlobStor) Close(ctx context.Context) error {
 	for i := range b.storage {
 		err := b.storage[i].Storage.Close(ctx)
 		if err != nil {
-			b.log.Info(ctx, logs.BlobstorCouldntCloseStorage, zap.String("error", err.Error()))
+			b.log.Info(ctx, logs.BlobstorCouldntCloseStorage, zap.Error(err))
 			if firstErr == nil {
 				firstErr = err
 			}

pkg/local_object_storage/blobstor/exists.go

@@ -75,7 +75,7 @@ func (b *BlobStor) Exists(ctx context.Context, prm common.ExistsPrm) (common.Exi
 	for _, err := range errors[:len(errors)-1] {
 		b.log.Warn(ctx, logs.BlobstorErrorOccurredDuringObjectExistenceChecking,
 			zap.Stringer("address", prm.Address),
-			zap.String("error", err.Error()),
+			zap.Error(err),
 			zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
 	}
 

pkg/local_object_storage/blobstor/fstree/fstree.go

@@ -153,7 +153,7 @@ func (t *FSTree) iterate(ctx context.Context, depth uint64, curPath []string, pr
 	if err != nil {
 		if prm.IgnoreErrors {
 			t.log.Warn(ctx, logs.BlobstorErrorOccurredDuringTheIteration,
-				zap.String("err", err.Error()),
+				zap.Error(err),
 				zap.String("directory_path", dirPath))
 			return nil
 		}
@@ -202,7 +202,7 @@ func (t *FSTree) iterate(ctx context.Context, depth uint64, curPath []string, pr
 			if prm.IgnoreErrors {
 				t.log.Warn(ctx, logs.BlobstorErrorOccurredDuringTheIteration,
 					zap.Stringer("address", addr),
-					zap.String("err", err.Error()),
+					zap.Error(err),
 					zap.String("path", path))
 				continue
 			}

pkg/local_object_storage/blobstor/iterate.go

@@ -45,7 +45,7 @@ func (b *BlobStor) Iterate(ctx context.Context, prm common.IteratePrm) (common.I
 				b.log.Warn(ctx, logs.BlobstorErrorOccurredDuringTheIteration,
 					zap.String("storage_path", b.storage[i].Storage.Path()),
 					zap.String("storage_type", b.storage[i].Storage.Type()),
-					zap.String("err", err.Error()))
+					zap.Error(err))
 				continue
 			}
 			return common.IterateRes{}, fmt.Errorf("blobstor iterator failure: %w", err)