feat(core): improve in-memory validation, FatturaPA detection coverage, and published type compatibility

ts/formats/validation/schematron.downloader.ts

@@ -139,7 +139,8 @@ export class SchematronDownloader {
       console.log(`Successfully downloaded: ${fileName}`);
       return filePath;
     } catch (error) {
-      throw new Error(`Failed to download ${source.name}: ${error.message}`);
+      const errorMessage = error instanceof Error ? error.message : String(error);
+      throw new Error(`Failed to download ${source.name}: ${errorMessage}`);
     }
   }
   
@@ -160,7 +161,8 @@ export class SchematronDownloader {
         const path = await this.download(source);
         paths.push(path);
       } catch (error) {
-        console.warn(`Failed to download ${source.name}: ${error.message}`);
+        const errorMessage = error instanceof Error ? error.message : String(error);
+        console.warn(`Failed to download ${source.name}: ${errorMessage}`);
       }
     }
     
@@ -209,7 +211,8 @@ export class SchematronDownloader {
         }
       }
     } catch (error) {
-      console.warn(`Failed to list cached files: ${error.message}`);
+      const errorMessage = error instanceof Error ? error.message : String(error);
+      console.warn(`Failed to list cached files: ${errorMessage}`);
     }
     
     return files;
@@ -230,7 +233,8 @@ export class SchematronDownloader {
       
       console.log('Schematron cache cleared');
     } catch (error) {
-      console.warn(`Failed to clear cache: ${error.message}`);
+      const errorMessage = error instanceof Error ? error.message : String(error);
+      console.warn(`Failed to clear cache: ${errorMessage}`);
     }
   }
   
@@ -296,9 +300,10 @@ export async function downloadISOSkeletons(targetDir: string = 'assets_downloade
       
       console.log(`Downloaded: ${name}`);
     } catch (error) {
-      console.warn(`Failed to download ${name}: ${error.message}`);
+      const errorMessage = error instanceof Error ? error.message : String(error);
+      console.warn(`Failed to download ${name}: ${errorMessage}`);
     }
   }
   
   console.log('ISO Schematron skeleton download complete');
-}
+}