No propagate, fix 'attachment save' cancel

* Quote: Ensure that clicks don't propagate to parent
* Attachment Save: Check for null; returned if user cancels out

js/views/conversation_view.js

@@ -1804,7 +1804,10 @@
             saveAttachmentToDisk,
             timestamp,
           });
+
+          if (fullPath) {
             this.showToast(Whisper.FileSavedToast, { fullPath });
+          }
         };
 
         const onItemClick = async ({ message, attachment, type }) => {
@@ -2001,7 +2004,10 @@
         saveAttachmentToDisk,
         timestamp,
       });
+
+      if (fullPath) {
         this.showToast(Whisper.FileSavedToast, { fullPath });
+      }
     },
 
     async displayTapToViewMessage(messageId) {
@@ -2205,7 +2211,10 @@
           saveAttachmentToDisk,
           timestamp: options.message.get('sent_at'),
         });
+
+        if (fullPath) {
           this.showToast(Whisper.FileSavedToast, { fullPath });
+        }
       };
 
       const props = {

ts/components/conversation/Quote.tsx

@@ -105,6 +105,15 @@ export class Quote extends React.Component<Props, State> {
       onClick();
     }
   };
+  public handleClick = (event: React.MouseEvent<HTMLButtonElement>) => {
+    const { onClick } = this.props;
+
+    if (onClick) {
+      event.preventDefault();
+      event.stopPropagation();
+      onClick();
+    }
+  };
 
   public handleImageError = () => {
     // tslint:disable-next-line no-console
@@ -381,7 +390,7 @@ export class Quote extends React.Component<Props, State> {
         )}
       >
         <button
-          onClick={onClick}
+          onClick={this.handleClick}
           onKeyDown={this.handleKeyDown}
           className={classNames(
             'module-quote',

ts/types/Attachment.ts

@@ -339,7 +339,7 @@ export const save = async ({
     name: string;
   }) => Promise<{ name: string; fullPath: string }>;
   timestamp?: number;
-}): Promise<string> => {
+}): Promise<string | null> => {
   if (!attachment.path && !attachment.data) {
     throw new Error('Attachment had neither path nor data');
   }
@@ -349,12 +349,16 @@ export const save = async ({
     : attachment.data;
   const name = getSuggestedFilename({ attachment, timestamp, index });
 
-  const { fullPath } = await saveAttachmentToDisk({
+  const result = await saveAttachmentToDisk({
     data,
     name,
   });
 
-  return fullPath;
+  if (!result) {
+    return null;
+  }
+
+  return result.fullPath;
 };
 
 export const getSuggestedFilename = ({