catch error and show linux udev dialog

app/app.html

@@ -1384,6 +1384,12 @@ <h3>
       <h1>Please connect your OnlyKey</h1>
     </dialog>
 
+    <dialog id="udev-dialog" class="silver-gradient-bg">
+      <h1>Error connecting</h1>
+      <h3>Do you need a UDEV rule?</h3>
+      <p>See the <u><a class="external" href="https://docs.onlykey.io/linux.html#udev-rule">OnlyKey for Linux docs</a></u> for more info.</p>
+    </dialog>
+
     <dialog id="working-dialog" class="silver-gradient-bg">
       <h1>Working...</h1>
       <h2>Please wait</h2>

app/scripts/external-links.js

@@ -1,14 +1,19 @@
 const openMethod = typeof nw === 'undefined' ? window.open : nw.Shell.openExternal;
 
-// Formerly checked for 'external' in classList. Now fires for all https:// links.
-document.querySelector('#main').addEventListener('click', evt => {
+const handler = evt => {
     let href = evt.target && evt.target.href;
     if (!href) href = evt.target && evt.target.offsetParent && evt.target.offsetParent.href;
     if (!href) href = evt.path && evt.path[1] && evt.path[1].href;
-
+
+    // Formerly checked for 'external' in classList. Now fires for all https:// links.
     if (!!href && href.indexOf('https://') == 0) {
         openMethod(href);
         evt.preventDefault && evt.preventDefault();
         evt.stopPropgation && evt.stopPropagation();
     }
-});
+};
+
+[
+    '#main',
+    '#udev-dialog',
+].forEach(sel => document.querySelector(sel).addEventListener('click', handler));

app/scripts/onlyKey/OnlyKeyComm.js

@@ -6,6 +6,9 @@ if (desktopApp) {
   request = require("request");
 }
 
+const os = require('os');
+const linux = os.platform() === 'linux';
+
 let backupsigFlag = -1;
 let fwchecked = false;
 let dialog;
@@ -1077,6 +1080,7 @@ var ui = {
   lockedDialogDuo: null,
   workingDialog: null,
   disconnectedDialog: null,
+  udevDialog: null,
   main: null,
 };
 
@@ -1267,9 +1271,23 @@ var connectDevice = async function (device) {
 
   chromeHid.connect(deviceId, async function (connectInfo) {
     if (chrome.runtime.lastError) {
-      console.error("ERROR CONNECTING:", chrome.runtime.lastError);
+      console.error(`ERROR CONNECTING: ${chrome.runtime.lastError.message}`, device);
+      if (linux) {
+        dialog.open(ui.udevDialog);
+      } else {
+        if (confirm(`ERROR: ${chrome.runtime.lastError.message}\n\nRetry?`)) {
+          return await connectDevice(device);
+        }
+      }
     } else if (!connectInfo) {
       console.warn("Unable to connect to device.");
+      if (confirm(`ERROR: Unable to read device info.\n\nRetry?`)) {
+        return await connectDevice(device);
+      }
+    }
+
+    if (!connectInfo) {
+      return;
     }
 
     myOnlyKey.setConnection(connectInfo.connectionId);