fix: make defaultInit take function as header property

Author: mnorlin

src/openapi-typescript/fetch-factory.ts

@@ -64,7 +64,7 @@ function fetchFactory<Paths>(options?: InitParameters) {
 }
 
 function buildInit(
-  defaultInit: RequestInit,
+  defaultInit: Omit<RequestInit, "headers">,
   options: AllFetchOptions,
   headers: HeadersInit
 ): RequestInit {

src/openapi-typescript/header-builder.ts

@@ -1,9 +1,9 @@
 export function buildHeaders(
   resolvedPath: string,
   defaultHeaders?:
-    | RequestInitHeaders
-    | ((pathInfo: { resolvedPath: string }) => RequestInitHeaders),
-  headers?: RequestInitHeaders
+    | HeadersInit
+    | ((pathInfo: { resolvedPath: string }) => HeadersInit),
+  headers?: HeadersInit
 ) {
   const resolvedDefaultHeaders =
     typeof defaultHeaders === "function"
@@ -34,5 +34,3 @@ function headerToEntries(
 
   return Object.entries(headers);
 }
-
-type RequestInitHeaders = Headers | [string, string][] | Record<string, string>;

src/types/common.ts

@@ -1,6 +1,10 @@
 export type InitParameters = {
   baseUrl?: string;
-  defaultInit?: Omit<RequestInit, "method">;
+  defaultInit?: Omit<RequestInit, "method" | "headers"> & {
+    headers:
+      | HeadersInit
+      | ((pathInfo: { resolvedPath: string }) => HeadersInit);
+  };
   fetchMethod?: typeof fetch;
   parameterSerialization?: {
     path?: { explode?: boolean; style?: PathSerializationStyle };