Misc Chat fixes

• fix chat back button size to make it easier to hit (especially on mobile)
• fix chat notifications being marked as read too eagerly, I've had the problem where I've missed quite a few chat messages because they arrive roughly at the same time as I'm leaving the chat view, so it has just enough time to register the messages as read but I didn't have enough time to even notice the new messages. Note that there was some double logic in how things get marked as read, that's why some "forceRead" calls were cut out, it still works like you'd expect.
• fix promiseinterval erroring when not getting a promise
• fix an error about lastMessage not having an account property, this was because of a typo with "account.id" instead of "account_id"

src/components/chat/chat.js

@@ -21,6 +21,7 @@ library.add(
 const BOTTOMED_OUT_OFFSET = 10
 const JUMP_TO_BOTTOM_BUTTON_VISIBILITY_OFFSET = 150
 const SAFE_RESIZE_TIME_OFFSET = 100
+const MARK_AS_READ_DELAY = 1500
 
 const Chat = {
   components: {
@@ -104,7 +105,7 @@ const Chat = {
       const bottomedOutBeforeUpdate = this.bottomedOut(BOTTOMED_OUT_OFFSET)
       this.$nextTick(() => {
         if (bottomedOutBeforeUpdate) {
-          this.scrollDown({ forceRead: !document.hidden })
+          this.scrollDown()
         }
       })
     },
@@ -210,7 +211,7 @@ const Chat = {
       this.$nextTick(() => {
         scrollable.scrollTo({ top: scrollable.scrollHeight, left: 0, behavior })
       })
-      if (forceRead || this.newMessageCount > 0) {
+      if (forceRead) {
         this.readChat()
       }
     },
@@ -235,12 +236,18 @@ const Chat = {
       } else if (this.bottomedOut(JUMP_TO_BOTTOM_BUTTON_VISIBILITY_OFFSET)) {
         this.jumpToBottomButtonVisible = false
         if (this.newMessageCount > 0) {
-          this.readChat()
+          // Use a delay before marking as read to prevent situation where new messages
+          // arrive just as you're leaving the view and messages that you didn't actually
+          // get to see get marked as read.
+          window.setTimeout(() => {
+            // Don't mark as read if the element doesn't exist, user has left chat view
+            if (this.$el) this.readChat()
+          }, MARK_AS_READ_DELAY)
         }
       } else {
         this.jumpToBottomButtonVisible = true
       }
-    }, 100),
+    }, 200),
     handleScrollUp (positionBeforeLoading) {
       const positionAfterLoading = getScrollPosition(this.$refs.scrollable)
       this.$refs.scrollable.scrollTo({