remove unneeded check for cycles

Author: IvanGoncharov

src/execution/__tests__/abstract-test.ts

@@ -752,7 +752,7 @@ describe('Execute: Handles execution of abstract types', () => {
     // FIXME: workaround since we can't inject resolveType into SDL
     petType.resolveType = () => 'Pet';
     expectError().toEqual(
-      'Abstract type resolution for "Named" for field "Query.named" failed. Encountered abstract type "Pet" resolved to "Pet", causing a cycle.',
+      'Abstract type resolution for "Named" for field "Query.named" failed. Interface type "Pet" is not a subtype of encountered interface type "Named".',
     );
   });
 });

src/execution/execute.ts

@@ -840,7 +840,6 @@ function resolveType(
   fieldNodes: ReadonlyArray<FieldNode>,
   info: GraphQLResolveInfo,
   result: unknown,
-  encounteredTypeNames: Set<string> = new Set(),
 ): GraphQLObjectType | Promise<GraphQLObjectType> {
   const resolveTypeFn = abstractType.resolveType ?? exeContext.typeResolver;
   const contextValue = exeContext.contextValue;
@@ -861,7 +860,6 @@ function resolveType(
         fieldNodes,
         info,
         result,
-        encounteredTypeNames,
       ),
     );
   }
@@ -873,7 +871,6 @@ function resolveType(
     fieldNodes,
     info,
     result,
-    encounteredTypeNames,
   );
 }
 
@@ -885,7 +882,6 @@ function deriveRuntimeType(
   fieldNodes: ReadonlyArray<FieldNode>,
   info: GraphQLResolveInfo,
   result: unknown,
-  encounteredTypeNames: Set<string>,
 ): GraphQLObjectType | Promise<GraphQLObjectType> {
   if (runtimeTypeName == null) {
     throw new GraphQLError(
@@ -913,14 +909,6 @@ function deriveRuntimeType(
     );
   }
 
-  if (encounteredTypeNames.has(runtimeTypeName)) {
-    throw new GraphQLError(
-      `Abstract type resolution for "${returnType.name}" for field "${info.parentType.name}.${info.fieldName}" failed. ` +
-        `Encountered abstract type "${currentAbstractType.name}" resolved to "${runtimeTypeName}", causing a cycle.`,
-    );
-  }
-  encounteredTypeNames.add(runtimeTypeName);
-
   const runtimeType = exeContext.schema.getType(runtimeTypeName);
   if (runtimeType == null) {
     throw new GraphQLError(
@@ -946,7 +934,6 @@ function deriveRuntimeType(
       fieldNodes,
       info,
       result,
-      encounteredTypeNames,
     );
   }