From 419a05e801da688a1d0917a6bf16d468e6362a3d Mon Sep 17 00:00:00 2001
From: Florian Dold <florian.dold@gmail.com>
Date: Wed, 9 Aug 2017 16:51:25 +0200
Subject: [PATCH] fix errors in injection

Sometimes chrome reports a different URL for a tab than what it is
internally displaying (e.g. for error pages).  Previously this lead to a
"scary" error message being logged.
---
 src/webex/wxBackend.ts | 39 +++++++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/src/webex/wxBackend.ts b/src/webex/wxBackend.ts
index a8b725495..261477386 100644
--- a/src/webex/wxBackend.ts
+++ b/src/webex/wxBackend.ts
@@ -525,6 +525,24 @@ async function reinitWallet() {
 }
 
 
+/**
+ * Inject a script into a tab.  Gracefully logs errors
+ * and works around a bug where the tab's URL does not match the internal URL,
+ * making the injection fail in a confusing way.
+ */
+function injectScript(tabId: number, details: chrome.tabs.InjectDetails, actualUrl: string): void {
+  chrome.tabs.executeScript(tabId, details,  () => {
+    // Required to squelch chrome's "unchecked lastError" warning.
+    // Sometimes chrome reports the URL of a tab as http/https but
+    // injection fails.  This can happen when a page is unloaded or
+    // shows a "no internet" page etc.
+    if (chrome.runtime.lastError) {
+      console.warn("injection failed on page", actualUrl, chrome.runtime.lastError.message);
+    }
+  });
+}
+
+
 /**
  * Main function to run for the WebExtension backend.
  *
@@ -548,16 +566,17 @@ export async function wxMain() {
         return;
       }
       const uri = new URI(tab.url);
-      if (uri.protocol() === "http" || uri.protocol() === "https") {
-        console.log("injecting into existing tab", tab.id);
-        chrome.tabs.executeScript(tab.id, { file: "/dist/contentScript-bundle.js" });
-        const code = `
-          if (("taler" in window) || document.documentElement.getAttribute("data-taler-nojs")) {
-            document.dispatchEvent(new Event("taler-probe-result"));
-          }
-        `;
-        chrome.tabs.executeScript(tab.id, { code, runAt: "document_idle" });
+      if (uri.protocol() !== "http" && uri.protocol() !== "https") {
+        return;
       }
+      console.log("injecting into existing tab", tab.id, "with url", uri.href(), "protocol", uri.protocol());
+      injectScript(tab.id, { file: "/dist/contentScript-bundle.js" }, uri.href());
+      const code = `
+        if (("taler" in window) || document.documentElement.getAttribute("data-taler-nojs")) {
+          document.dispatchEvent(new Event("taler-probe-result"));
+        }
+      `;
+      injectScript(tab.id, { code, runAt: "document_idle" }, uri.href());
     }
   });
 
@@ -598,7 +617,7 @@ export async function wxMain() {
             document.dispatchEvent(new Event("taler-probe-result"));
           }
         `;
-        chrome.tabs.executeScript(tab.id!, { code, runAt: "document_start" });
+        injectScript(tab.id!, { code, runAt: "document_start" }, uri.href());
       });
     };