Correct content type checks on client

Author: DmitryAstafyev

application/client/src/app/module/ipc.ts

@@ -94,5 +94,5 @@ export interface Clipboard {
      * @param mime - MIME type of the data (e.g. `text/plain`, `image/png`).
      * @param data - Content as an ArrayBuffer.
      */
-    write(mime: string, data: ArrayBuffer): Promise<void>;
+    write(mime: string | undefined, data: ArrayBuffer): Promise<void>;
 }

application/client/src/app/ui/views/sidebar/attachments/preview/image/component.ts

@@ -206,13 +206,14 @@ export class Preview extends ChangesDetector implements AfterViewInit, AfterCont
                     this.log().warn(`Fail to fetch image as Blob`);
                     return;
                 }
+                const contentType = response.type.trim();
                 response
                     .arrayBuffer()
                     .then((buffer) => {
                         // We are using native clipboard API, but not browser one (navigator.clipboard)
                         // to avoid possible issues with size of blob.
                         window.electron.clipboard
-                            .write(response.type || 'application/octet-stream', buffer)
+                            .write(contentType.length > 0 ? contentType : undefined, buffer)
                             .catch((err: Error) => {
                                 this.log().warn(
                                     `Fail to copy image into clipboard: ${err.message}`,