Update src/lib/sb-file-uploader-hoc.jsx

src/lib/sb-file-uploader-hoc.jsx

@@ -141,7 +141,7 @@ const SBFileUploaderHOC = function (WrappedComponent) {
                     // Don't update file handle until after confirming replace.
                     const handle = thisFileInput.handle;
                     if (handle) {
-                        if (this.fileToUpload.name.endsWith('.pm') || this.fileToUpload.name.endsWith('.pmp')) {
+                        if (this.fileToUpload.name.endsWith('.txt') || this.fileToUpload.name.endsWith('.pm') || this.fileToUpload.name.endsWith('.pmp')) {
                             this.props.onSetFileHandle(handle);
                         } else {
                             this.props.onSetFileHandle(null);