Auto merge of #12539 - johannhof:error-page, r=jdm

Improve page load error information

Fixes #8640.

This commit adds a neterror page that displays really really basic
information about what went wrong with your request, which is an
improvement over the current state of blank page.

It also fixes the problem of certificate validation errors not
triggering the cert error page, since for some reason the function
string seems to have turned lowercase.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #8640.

- [x] These changes do not require tests because I'm not sure how to test this, suggestions welcome!

r?@jdm

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1 files changed, 14 insertions, 3 deletions

diff --git a/components/script/dom/servohtmlparser.rs b/components/script/dom/servohtmlparser.rs
index 884ac6c8653..a28612416fc 100644
--- a/components/script/dom/servohtmlparser.rs
+++ b/components/script/dom/servohtmlparser.rs
@@ -171,13 +171,24 @@ impl AsyncResponseListener for ParserContext {
             Some(parser) => parser.root(),
             None => return,
         };
-        parser.r().document().finish_load(LoadType::PageSource(self.url.clone()));
 
-        if let Err(err) = status {
-            debug!("Failed to load page URL {}, error: {:?}", self.url, err);
+        if let Err(NetworkError::Internal(ref reason)) = status {
+            // Show an error page for network errors,
+            // certificate errors are handled earlier.
+            self.is_synthesized_document = true;
+            let parser = parser.r();
+            let page_bytes = read_resource_file("neterror.html").unwrap();
+            let page = String::from_utf8(page_bytes).unwrap();
+            let page = page.replace("${reason}", reason);
+            parser.pending_input().borrow_mut().push(page);
+            parser.parse_sync();
+        } else if let Err(err) = status {
             // TODO(Savago): we should send a notification to callers #5463.
+            debug!("Failed to load page URL {}, error: {:?}", self.url, err);
         }
 
+        parser.r().document().finish_load(LoadType::PageSource(self.url.clone()));
+
         parser.r().last_chunk_received().set(true);
         if !parser.r().is_suspended() {
             parser.r().parse_sync();