fix(exports): stabilize published types and compatibility with updated dependencies

ts/skr.api.ts

@@ -534,6 +534,10 @@ export class SkrApi {
    */
   private async generatePdfReports(exporter: SkrExport, options: IExportOptions): Promise<void> {
     if (!this.reports) throw new Error('Reports not initialized');
+    const skrType = this.currentSKRType;
+    if (!skrType) {
+      throw new Error('API not initialized. Call initialize() first.');
+    }
 
     const pdfOptions: IPdfReportOptions = {
       companyName: options.companyInfo?.name || 'Unternehmen',
@@ -554,19 +558,19 @@ export class SkrApi {
       const trialBalance = await this.reports.getTrialBalance({
         dateFrom: options.dateFrom,
         dateTo: options.dateTo,
-        skrType: this.currentSKRType
+        skrType,
       });
 
       const incomeStatement = await this.reports.getIncomeStatement({
         dateFrom: options.dateFrom,
         dateTo: options.dateTo,
-        skrType: this.currentSKRType
+        skrType,
       });
 
       const balanceSheet = await this.reports.getBalanceSheet({
         dateFrom: options.dateFrom,
         dateTo: options.dateTo,
-        skrType: this.currentSKRType
+        skrType,
       });
 
       // Generate PDFs
@@ -702,7 +706,7 @@ export class SkrApi {
         const transaction = await this.postTransaction(transactions[i]);
         results.push(transaction);
       } catch (error) {
-        errors.push({ index: i, error: error.message });
+        errors.push({ index: i, error: error instanceof Error ? error.message : String(error) });
       }
     }
 
@@ -735,7 +739,7 @@ export class SkrApi {
         const account = await this.createAccount(accounts[i]);
         results.push(account);
       } catch (error) {
-        errors.push({ index: i, error: error.message });
+        errors.push({ index: i, error: error instanceof Error ? error.message : String(error) });
       }
     }