fixup! Fix typings of at methods

Author: keijokapp

lib/database.ts

@@ -47,7 +47,7 @@ export default class Database<KeyIn = NativeValue, KeyOut = Buffer, ValIn = Nati
   at<CKI, CKO>(prefix: KeyIn | null | undefined, keyXf: Transformer<CKI, CKO>, valueXf?: undefined): Database<CKI, CKO, ValIn, ValOut>;
   at<CVI, CVO>(prefix: KeyIn | null | undefined, keyXf: undefined, valueXf: Transformer<CVI, CVO>): Database<KeyIn, KeyOut, CVI, CVO>;
   at<CKI, CKO, CVI, CVO>(prefix: KeyIn | null | undefined, keyXf: Transformer<CKI, CKO>, valueXf: Transformer<CVI, CVO>): Database<CKI, CKO, CVI, CVO>;
-  at<CKI, CKO>(prefix: KeyIn | null | undefined, keyXf: Transformer<CKI, CKO>, valueXf?: undefined):
+  at<CKI, CKO>(prefix: KeyIn | null | undefined, keyXf?: Transformer<CKI, CKO>, valueXf?: undefined):
     | Database<KeyIn, KeyOut, ValIn, ValOut>
     | Database<CKI, CKO, ValIn, ValOut>;
   at<CVI, CVO>(prefix: KeyIn | null | undefined, keyXf: undefined, valueXf?: Transformer<CVI, CVO>):

lib/subspace.ts

@@ -45,7 +45,7 @@ export default class Subspace<KeyIn = NativeValue, KeyOut = Buffer, ValIn = Nati
   at<CKI, CKO>(prefix: KeyIn | null | undefined, keyXf: Transformer<CKI, CKO>, valueXf?: undefined): Subspace<CKI, CKO, ValIn, ValOut>;
   at<CVI, CVO>(prefix: KeyIn | null | undefined, keyXf: undefined, valueXf: Transformer<CVI, CVO>): Subspace<KeyIn, KeyOut, CVI, CVO>;
   at<CKI, CKO, CVI, CVO>(prefix: KeyIn | null | undefined, keyXf: Transformer<CKI, CKO>, valueXf: Transformer<CVI, CVO>): Subspace<CKI, CKO, CVI, CVO>;
-  at<CKI, CKO>(prefix: KeyIn | null | undefined, keyXf: Transformer<CKI, CKO>, valueXf?: undefined):
+  at<CKI, CKO>(prefix: KeyIn | null | undefined, keyXf?: Transformer<CKI, CKO>, valueXf?: undefined):
     | Subspace<KeyIn, KeyOut, ValIn, ValOut>
     | Subspace<CKI, CKO, ValIn, ValOut>;
   at<CVI, CVO>(prefix: KeyIn | null | undefined, keyXf: undefined, valueXf?: Transformer<CVI, CVO>):