Telemetry: fix error logging bugs, [object Object] and [object HTMLMediaElement]

src/main/index.js

@@ -78,8 +78,8 @@ function init () {
     // Report uncaught exceptions
     process.on('uncaughtException', (err) => {
       console.error(err)
-      var errJSON = {message: err.message, stack: err.stack}
-      windows.main.dispatch('uncaughtError', 'main', errJSON)
+      var error = {message: err.message, stack: err.stack}
+      windows.main.dispatch('uncaughtError', 'main', error)
     })
   })
 

src/renderer/lib/telemetry.js

@@ -119,23 +119,42 @@ function getApproxNumTorrents (state) {
 }
 
 // An uncaught error happened in the main process or in one of the windows
-function logUncaughtError (procName, err) {
+function logUncaughtError (procName, e) {
   // Not initialized yet? Ignore.
   // Hopefully uncaught errors immediately on startup are fixed in dev
   if (!telemetry) return
 
-  var message, stack
-  if (err instanceof Error) {
-    message = err.message
-    // Remove the first part of each file path in the stack trace.
-    // - Privacy: remove personal info like C:\Users\<full name>
-    // - Aggregation: this lets us find which stacktraces occur often
-    stack = err.stack.replace(/\(.*app.asar/g, '(...')
+  var message
+  var stack = ''
+  if (e.message) {
+    // err is either an Error or a plain object {message, stack}
+    message = e.message
+    stack = e.stack
+  } else if (e.error) {
+    // Uncaught Javascript errors (window.onerror), err is an ErrorEvent
+    if (!e.error.message) {
+      message = 'Unexpected ErrorEvent.error: ' + Object.keys(e.error).join(' ')
+    } else {
+      message = e.error.message
+      stack = e.error.stack
+    }
   } else {
-    message = String(err)
-    stack = ''
+    // Resource errors (captured element.onerror), err is an Event
+    if (!e.target) {
+      message = 'Unexpected unknown error'
+    } else if (!e.target.error) {
+      message = 'Unexpected resource loading error: ' + getElemString(e.target)
+    } else {
+      message = 'Resource error ' + getElemString(e.target) + ': ' + e.target.error.code
+    }
   }
 
+  // Remove the first part of each file path in the stack trace.
+  // - Privacy: remove personal info like C:\Users\<full name>
+  // - Aggregation: this lets us find which stacktraces occur often
+  if (stack && typeof stack === 'string') stack = stack.replace(/\(.*app.asar/g, '(...')
+  else if (stack) stack = 'Unexpected stack: ' + stack
+
   // We need to POST the telemetry object, make sure it stays < 100kb
   if (telemetry.uncaughtErrors.length > 20) return
   if (message.length > 1000) message = message.substring(0, 1000)
@@ -147,6 +166,15 @@ function logUncaughtError (procName, err) {
   telemetry.uncaughtErrors.push({process: procName, message, stack, version})
 }
 
+// Turns a DOM element into a string, eg "DIV.my-class.visible"
+function getElemString (elem) {
+  var ret = elem.tagName
+  try {
+    ret += '.' + Array.from(elem.classList).join('.')
+  } catch (e) {}
+  return ret
+}
+
 // The user pressed play. It either worked, timed out, or showed the
 // 'Play in VLC' codec error
 function logPlayAttempt (result) {

src/renderer/main.js

@@ -116,7 +116,8 @@ function onState (err, _state) {
 
   // Log uncaught JS errors
   window.addEventListener('error',
-    (e) => telemetry.logUncaughtError('window', e.error || e.target), true)
+    (e) => telemetry.logUncaughtError('window', e),
+    true /* capture */)
 
   // Done! Ideally we want to get here < 500ms after the user clicks the app
   sound.play('STARTUP')