Warn on invalid JSON file (#1159)

* add error dialog

* show error modal on file dnd

* add locales

* Update src/locales/en.json

Co-Authored-By: Lipis <lipiridis@gmail.com>

* Update src/data/blob.ts

* Update src/data/blob.ts

* fix titles, update snapshots

* make modal smaller

* fix dnd wrong file type

* reset errorMessage

Co-authored-by: Faustino Kialungila <faustino.kialungila@gmail.com>
Co-authored-by: Lipis <lipiridis@gmail.com>

src/appState.ts

@@ -6,6 +6,7 @@ export const DEFAULT_FONT = "20px Virgil";
 export function getDefaultAppState(): AppState {
   return {
     isLoading: false,
+    errorMessage: null,
     draggingElement: null,
     resizingElement: null,
     multiElement: null,
@@ -52,6 +53,7 @@ export function clearAppStateForLocalStorage(appState: AppState) {
     collaborators,
     isCollaborating,
     isLoading,
+    errorMessage,
     ...exportedState
   } = appState;
   return exportedState;