fix: improve types (#753)

Author: kyarik

src/index.ts

@@ -1,10 +1,8 @@
 import type { IncomingMessage, ServerResponse } from 'http';
 
 import type {
-  ASTVisitor,
   DocumentNode,
   ValidationRule,
-  ValidationContext,
   ExecutionArgs,
   ExecutionResult,
   FormattedExecutionResult,
@@ -15,7 +13,6 @@ import type {
 } from 'graphql';
 import accepts from 'accepts';
 import httpError from 'http-errors';
-import type { HttpError } from 'http-errors';
 import {
   Source,
   GraphQLError,
@@ -78,7 +75,7 @@ export interface OptionsData {
    * An optional array of validation rules that will be applied on the document
    * in additional to those defined by the GraphQL spec.
    */
-  validationRules?: ReadonlyArray<(ctx: ValidationContext) => ASTVisitor>;
+  validationRules?: ReadonlyArray<ValidationRule>;
 
   /**
    * An optional function which will be used to validate instead of default `validate`
@@ -196,7 +193,7 @@ export function graphqlHTTP(options: Options): Middleware {
     // Higher scoped variables are referred to at various stages in the asynchronous state machine below.
     let params: GraphQLParams | undefined;
     let showGraphiQL = false;
-    let graphiqlOptions;
+    let graphiqlOptions: GraphiQLOptions | undefined;
     let formatErrorFn = formatError;
     let pretty = false;
     let result: ExecutionResult;
@@ -218,7 +215,7 @@ export function graphqlHTTP(options: Options): Middleware {
       }
 
       // Then, resolve the Options to get OptionsData.
-      const optionsData: OptionsData = await resolveOptions(params);
+      const optionsData = await resolveOptions(params);
 
       // Collect information from the options data object.
       const schema = optionsData.schema;
@@ -277,7 +274,7 @@ export function graphqlHTTP(options: Options): Middleware {
       }
 
       // Parse source to AST, reporting any syntax error.
-      let documentAST;
+      let documentAST: DocumentNode;
       try {
         documentAST = parseFn(new Source(query, 'GraphQL request'));
       } catch (syntaxError: unknown) {
@@ -357,7 +354,7 @@ export function graphqlHTTP(options: Options): Middleware {
       }
     } catch (rawError: unknown) {
       // If an error was caught, report the httpError status, or 500.
-      const error: HttpError = httpError(
+      const error = httpError(
         500,
         /* istanbul ignore next: Thrown by underlying library. */
         rawError instanceof Error ? rawError : String(rawError),