!fixup this if working

public/scripts/network.js

@@ -1082,20 +1082,9 @@ class PeersManager {
         this.peers[detail.to]._respondToFileTransferRequest(detail.accepted);
     }
 
-    _onFilesSelected(message) {
+    async _onFilesSelected(message) {
-        let inputFiles = Array.from(message.files);
+        let files = await mime.addMissingMimeTypesToFiles(message.files);
-        delete message.files;
+        await this.peers[message.to].requestFileTransfer(files);
-        let files = [];
-        const l = inputFiles.length;
-        for (let i=0; i<l; i++) {
-            // when filetype is empty guess via suffix
-            const inputFile = inputFiles.shift();
-            const file = inputFile.type
-                ? inputFile
-                : new File([inputFile], inputFile.name, {type: mime.getMimeByFilename(inputFile.name)});
-            files.push(file)
-        }
-        this.peers[message.to].requestFileTransfer(files);
     }
 
     _onSendText(message) {

public/scripts/ui.js

@@ -272,6 +272,8 @@ class PeersUI {
                 descriptorInstructions = Localization.getTranslation("instructions.activate-share-mode-shared-file");
             }
 
+            files = await mime.addMissingMimeTypesToFiles(files);
+
             if (files[0].type.split('/')[0] === 'image') {
                 getResizedImageDataUrl(files[0], 80, null, 0.9)
                     .then(dataUrl => {

public/scripts/util.js

@@ -104,12 +104,7 @@ const zipper = (() => {
 
 const mime = (() => {
 
-    return {
+    const suffixToMimeMap = {
-        getMimeByFilename(filename) {
-            try {
-                const arr = filename.split('.');
-                const suffix = arr[arr.length - 1].toLowerCase();
-                return {
         "cpl": "application/cpl+xml",
         "gpx": "application/gpx+xml",
         "gz": "application/gzip",
@@ -397,12 +392,27 @@ const mime = (() => {
         "vob": "video/x-ms-vob",
         "wmv": "video/x-ms-wmv",
         "avi": "video/x-msvideo",
-                    "*": "video/x-sgi-movie",
+        "*": "video/x-sgi-movie"
-                }[suffix] || '';
-            } catch (e) {
-                console.error(e);
-                return '';
     }
+
+    return {
+        async guessMimeByFilename(filename) {
+            const split = filename.split('.');
+            if (split.length === 1) {
+                // Filename does not include suffix
+                return "";
+            }
+            const suffix = split[split.length - 1].toLowerCase();
+            return suffixToMimeMap[suffix] || "";
+        },
+        async addMissingMimeTypesToFiles(files) {
+            // if filetype is empty guess via suffix otherwise leave unchanged
+            for (let i = 0; i < files.length; i++) {
+                if (!files[i].type) {
+                    files[i] = new File([files[i]], files[i].name, {type: await mime.guessMimeByFilename(files[i].name) || ""});
+                }
+            }
+            return files;
         }
     };