fix: support d&d of files without extension (#3168)

src/components/App.tsx

@@ -3626,9 +3626,18 @@ class App extends React.Component<ExcalidrawProps, AppState> {
 
     const file = event.dataTransfer?.files[0];
     if (
-      file?.type === "application/json" ||
-      file?.name.endsWith(".excalidraw")
+      file?.type === MIME_TYPES.excalidrawlib ||
+      file?.name?.endsWith(".excalidrawlib")
     ) {
+      Library.importLibrary(file)
+        .then(() => {
+          this.setState({ isLibraryOpen: false });
+        })
+        .catch((error) =>
+          this.setState({ isLoading: false, errorMessage: error.message }),
+        );
+      // default: assume an Excalidraw file regardless of extension/MimeType
+    } else {
       this.setState({ isLoading: true });
       if (supported) {
         try {
@@ -3640,23 +3649,7 @@ class App extends React.Component<ExcalidrawProps, AppState> {
           console.warn(error.name, error.message);
         }
       }
-      this.loadFileToCanvas(file);
-    } else if (
-      file?.type === MIME_TYPES.excalidrawlib ||
-      file?.name.endsWith(".excalidrawlib")
-    ) {
-      Library.importLibrary(file)
-        .then(() => {
-          this.setState({ isLibraryOpen: false });
-        })
-        .catch((error) =>
-          this.setState({ isLoading: false, errorMessage: error.message }),
-        );
-    } else {
-      this.setState({
-        isLoading: false,
-        errorMessage: t("alerts.couldNotLoadInvalidFile"),
-      });
+      await this.loadFileToCanvas(file);
     }
   };
 

src/data/blob.ts

@@ -1,5 +1,5 @@
 import { cleanAppStateForExport } from "../appState";
-import { EXPORT_DATA_TYPES, MIME_TYPES } from "../constants";
+import { EXPORT_DATA_TYPES } from "../constants";
 import { clearElementsForExport } from "../element";
 import { CanvasError } from "../errors";
 import { t } from "../i18n";
@@ -95,13 +95,7 @@ export const loadFromBlob = async (
         elements: clearElementsForExport(data.elements || []),
         appState: {
           theme: localAppState?.theme,
-          fileHandle:
-            blob.handle &&
-            ["application/json", MIME_TYPES.excalidraw].includes(
-              getMimeType(blob),
-            )
-              ? blob.handle
-              : null,
+          fileHandle: blob.handle ?? null,
           ...cleanAppStateForExport(data.appState || {}),
           ...(localAppState
             ? calculateScrollCenter(data.elements || [], localAppState, null)