fix(common): Fix the FormattedExecutionResult.errors type (#621)

Co-authored-by: Denis Badurina <[email protected]>

Author: pleunv

.changeset/eleven-bears-warn.md

@@ -0,0 +1,5 @@
+---
+'graphql-ws': patch
+---
+
+FormattedExecutionResult errors field returns GraphQLFormattedError

src/common.ts

@@ -163,7 +163,7 @@ export interface FormattedExecutionResult<
   Data = Record<string, unknown>,
   Extensions = Record<string, unknown>,
 > {
-  errors?: ReadonlyArray<FormattedExecutionResult> | undefined;
+  errors?: ReadonlyArray<GraphQLFormattedError> | undefined;
   data?: Data | null | undefined;
   hasNext?: boolean | undefined;
   extensions?: Extensions | undefined;