From 207257b827aaef109fd8d7c2e656ff8e4fac5d1a Mon Sep 17 00:00:00 2001
From: Jon Rohan <rohan@github.com>
Date: Tue, 2 Sep 2025 12:30:08 -0700
Subject: [PATCH 1/4] Refactor content type check for response handling

---
 src/include-fragment-element.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/include-fragment-element.ts b/src/include-fragment-element.ts
index c8e0280..807bf39 100644
--- a/src/include-fragment-element.ts
+++ b/src/include-fragment-element.ts
@@ -237,10 +237,6 @@ export class IncludeFragmentElement extends HTMLElement {
       if (response.status !== 200) {
         throw new Error(`Failed to load resource: the server responded with a status of ${response.status}`)
       }
-      const ct = response.headers.get('Content-Type')
-      if (!isWildcard(this.accept) && (!ct || !ct.includes(this.accept ? this.accept : 'text/html'))) {
-        throw new Error(`Failed to load resource: expected ${this.accept || 'text/html'} but was ${ct}`)
-      }
 
       const responseText: string = await response.text()
       let data: string | CSPTrustedHTMLToStringable = responseText
@@ -259,6 +255,10 @@ export class IncludeFragmentElement extends HTMLElement {
       // the `load()` promise to resolve _before_ these
       // events are fired.
       this.#task(['error', 'loadend'], error as Error)
+      const ct = response.headers.get('Content-Type')
+      if (!isWildcard(this.accept) && (!ct || !ct.includes(this.accept ? this.accept : 'text/html'))) {
+        throw new Error(`Failed to load resource: expected ${this.accept || 'text/html'} but was ${ct}`)
+      }
       throw error
     }
   }

From 62642dc40456f5e1b162dbd1205135b95bd85af3 Mon Sep 17 00:00:00 2001
From: Jon Rohan <rohan@github.com>
Date: Tue, 2 Sep 2025 14:50:34 -0700
Subject: [PATCH 2/4] Move content type check before general status !== 200

---
 src/include-fragment-element.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/include-fragment-element.ts b/src/include-fragment-element.ts
index 807bf39..64725cf 100644
--- a/src/include-fragment-element.ts
+++ b/src/include-fragment-element.ts
@@ -234,6 +234,10 @@ export class IncludeFragmentElement extends HTMLElement {
     try {
       await this.#task(['loadstart'])
       const response = await this.fetch(this.request())
+      const ct = response.headers.get('Content-Type')
+      if (!isWildcard(this.accept) && (!ct || !ct.includes(this.accept ? this.accept : 'text/html'))) {
+        throw new Error(`Failed to load resource: expected ${this.accept || 'text/html'} but was ${ct}`)
+      }
       if (response.status !== 200) {
         throw new Error(`Failed to load resource: the server responded with a status of ${response.status}`)
       }
@@ -255,10 +259,6 @@ export class IncludeFragmentElement extends HTMLElement {
       // the `load()` promise to resolve _before_ these
       // events are fired.
       this.#task(['error', 'loadend'], error as Error)
-      const ct = response.headers.get('Content-Type')
-      if (!isWildcard(this.accept) && (!ct || !ct.includes(this.accept ? this.accept : 'text/html'))) {
-        throw new Error(`Failed to load resource: expected ${this.accept || 'text/html'} but was ${ct}`)
-      }
       throw error
     }
   }

From c17ae31fd73c547e9d8f9166ae526acd45e7ba44 Mon Sep 17 00:00:00 2001
From: Jon Rohan <rohan@github.com>
Date: Tue, 2 Sep 2025 14:55:51 -0700
Subject: [PATCH 3/4] Update error message assertions in tests

---
 test/test.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/test.js b/test/test.js
index 19066e1..7e1728b 100644
--- a/test/test.js
+++ b/test/test.js
@@ -213,7 +213,7 @@ suite('include-fragment-element', function () {
       await el.data
       throw new Error('el.data did not throw')
     } catch (error) {
-      assert.match(error, /the server responded with a status of 406/)
+      assert.match(error, /expected text\/html but was text\/plain/)
     }
   })
 
@@ -343,7 +343,7 @@ suite('include-fragment-element', function () {
     assert.equal(event.bubbles, false)
     assert.equal(event.cancelable, false)
     assert.instanceOf(event.detail.error, Error)
-    assert.equal(event.detail.error.message, 'Failed to load resource: the server responded with a status of 500')
+    assert.equal(event.detail.error.message, 'Failed to load resource: expected text/html but was text/plain;charset=UTF-8')
   })
 
   test('adds is-error class on 500 status', async function () {

From c7b1ca135e3a28303e4df6ffa4c31469156bbdf9 Mon Sep 17 00:00:00 2001
From: Jon Rohan <rohan@github.com>
Date: Tue, 2 Sep 2025 14:58:11 -0700
Subject: [PATCH 4/4] Refactor error message assertion in test

---
 test/test.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/test/test.js b/test/test.js
index 7e1728b..9796278 100644
--- a/test/test.js
+++ b/test/test.js
@@ -343,7 +343,10 @@ suite('include-fragment-element', function () {
     assert.equal(event.bubbles, false)
     assert.equal(event.cancelable, false)
     assert.instanceOf(event.detail.error, Error)
-    assert.equal(event.detail.error.message, 'Failed to load resource: expected text/html but was text/plain;charset=UTF-8')
+    assert.equal(
+      event.detail.error.message,
+      'Failed to load resource: expected text/html but was text/plain;charset=UTF-8',
+    )
   })
 
   test('adds is-error class on 500 status', async function () {