correct type issues

src/Model/Global/fileTransferModel.ts

@@ -37,6 +37,7 @@ export default class FileTransferModel {
     };
 
     readonly prepareToSend = (): void => {
+	if (!this.transferData) return;
         this.direction = TransferDirections.Send;
         this.connectionModel.addChannel(this.transferData.channel);
     };
@@ -156,7 +157,7 @@ export default class FileTransferModel {
     };
 
     readonly prepareFileForSending = (filePath: string[]): string => {
-        const fileContent: string | undefined =
+        const fileContent: string | null =
             this.storageModel.read(filePath);
         if (fileContent == null) return "";
 
@@ -168,6 +169,8 @@ export default class FileTransferModel {
     };
 
     readonly sendFile = async (stringifiedFileData: string): Promise<void> => {
+	if (!this.transferData) return;
+
         const encryptedFileData: string = await encryptString(
             stringifiedFileData,
             this.transferData.key,

src/Model/Global/settingsModel.ts

@@ -6,10 +6,10 @@ export default class SettingsModel {
     readonly storageModel: StorageModel;
 
     // data
-    username: string;
-    firstDayOfWeek: string;
-    language: string;
-    theme: string;
+    username: string = "";
+    firstDayOfWeek: string = "";
+    language: string = "";
+    theme: string = "";
 
     // storage
     private readonly storeSetting = (
@@ -46,7 +46,7 @@ export default class SettingsModel {
     // load
     private readonly readSetting = (
         pathName: keyof typeof filePaths.settingsModel,
-    ): string => {
+    ): string|null=> {
         const path = StorageModel.getPath(
             StorageModelSubPaths.SettingsModel,
             filePaths.settingsModel[pathName],