Show error icon at startup if proxy check fails

If a proxy is required and we can't connect to S3, show the (sync) error
icon. For SSL certificate errors, which are the most common cause of
this, the panel includes a link to the SSL cert troubleshooting page.

chrome/content/zotero/xpcom/http.js

@@ -651,10 +651,13 @@ Zotero.HTTP = new function() {
 							dontCache: true
 						})
 						.catch(function (e) {
-							Components.utils.reportError(e);
-							var msg = "Error connecting to proxy -- proxied requests may not work";
-							Zotero.log(msg, 'error');
-							Zotero.debug(msg, 1);
+							// Show error icon at startup
+							if (e instanceof Zotero.HTTP.SecurityException) {
+								Zotero.proxyFailure = e;
+							}
+							Zotero.logError(e);
+							let msg = "Error connecting to proxy -- proxied requests may not work";
+							Zotero.logError(msg);
 						});
 						break;
 					}

chrome/content/zotero/zoteroPane.js

@@ -481,6 +481,18 @@ var ZoteroPane = new function()
 			Zotero.Prefs.set(pref, true);
 		}
 		
+		if (Zotero.proxyFailure) {
+			try {
+				Zotero.proxyFailure.message += "\n\n"
+					+ Zotero.getString('startupError.internetFunctionalityMayNotWork');
+				Zotero.Sync.Runner.updateIcons(Zotero.proxyFailure);
+				Zotero.proxyFailure = null;
+			}
+			catch (e) {
+				Zotero.logError(e);
+			}
+		}
+		
 		// Auto-sync on pane open or if new account
 		if (Zotero.Prefs.get('sync.autoSync') || Zotero.initAutoSync) {
 			yield Zotero.proxyAuthComplete;

chrome/locale/en-US/zotero/zotero.properties

@@ -185,6 +185,7 @@ startupError.incompatibleDBVersion         = This %1$S database requires %1$S %2
 startupError.zoteroVersionIsOlder.current	= Current version: %S
 startupError.zoteroVersionIsOlder.upgrade      = Please upgrade to the latest version from %S.
 startupError.databaseUpgradeError			= Database upgrade error
+startupError.internetFunctionalityMayNotWork = Functionality that depends on an internet connection may not work.
 
 date.relative.secondsAgo.one			= 1 second ago
 date.relative.secondsAgo.multiple		= %S seconds ago