fix: clear cache

lib/fetch/headers.js

@@ -241,6 +241,8 @@ class HeadersList {
    * @param {string} value
    */
   lowerCaseSet (name, value) {
+    this[kHeadersSortedMap] = null
+
     if (name === 'set-cookie') {
       this.cookies = [value]
     }
@@ -257,7 +259,14 @@ class HeadersList {
    * @param {string} name
    */
   delete (name) {
-    return this.lowerCaseDelete(name.toLowerCase())
+    this[kHeadersSortedMap] = null
+    name = name.toLowerCase()
+
+    if (name === 'set-cookie') {
+      this.cookies = null
+    }
+
+    this[kHeadersMap].delete(name)
   }
 
   /**
@@ -279,20 +288,22 @@ class HeadersList {
    * @returns {string | null}
    */
   get (name) {
-    const value = this[kHeadersMap].get(name.toLowerCase())
-
     // 1. If list does not contain name, then return null.
     // 2. Return the values of all headers in list whose name
     //    is a byte-case-insensitive match for name,
     //    separated from each other by 0x2C 0x20, in order.
-    return value === undefined ? null : value.value
+    return this[kHeadersMap].get(name.toLowerCase())?.value ?? null
   }
 
   /**
    * @param {string} name
    * @returns {string | null}
    */
   lowerCaseGet (name) {
+    // 1. If list does not contain name, then return null.
+    // 2. Return the values of all headers in list whose name
+    //    is a byte-case-insensitive match for name,
+    //    separated from each other by 0x2C 0x20, in order.
     return this[kHeadersMap].get(name)?.value ?? null
   }