refactor(app): simplify App initialization and rename PSPDFKit instance

- Initialize `currentDocument` and `currentReceiver` directly in constructor
- Replace `Instance` with `pdfKit` for clearer naming
- Remove redundant envelope/document loading in `init`
- Update all method references to use `this.pdfKit`

EnvelopeGenerator.Web/wwwroot/js/app.js

@@ -2,9 +2,9 @@ class App {
     constructor(envelopeKey, envelopeReceiver, documentBytes, licenseKey, locale, container) {
         this.container = container ?? `#${this.constructor.name.toLowerCase()}`;
         this.envelopeKey = envelopeKey
-        this.Instance = null
-        this.currentDocument = null
-        this.currentReceiver = null
+        this.pdfKit = null
+        this.currentDocument = envelopeReceiver.envelope.documents[0]
+        this.currentReceiver = envelopeReceiver.receiver
         this.signatureCount = 0;
         this.envelopeReceiver = envelopeReceiver;
         this.documentBytes = documentBytes;
@@ -12,51 +12,32 @@ class App {
         this.locale = locale;
     }
 
-    // This function will be called from the ShowEnvelope.razor page
-    // and will trigger loading of the Editor Interface
     async init() {
-        // Load the envelope from the database
-        this.currentDocument = this.envelopeReceiver.envelope.documents[0]
-        this.currentReceiver = this.envelopeReceiver.receiver
-
-        // Load the document from the filestore
-        const documentResponse = this.documentBytes
-
-        if (documentResponse.fatal || documentResponse.error) {
-            return Swal.fire({
-                title: 'Fehler',
-                text: 'Dokument konnte nicht geladen werden!',
-                icon: 'error',
-            })
-        }
-
-        const arrayBuffer = this.documentBytes
-
         // Load PSPDFKit
-        this.Instance = await UI.loadPSPDFKit(arrayBuffer, this.container, this.licenseKey, this.locale)
-        UI.addToolbarItems(this.Instance, this.handleClick.bind(this))
+        this.pdfKit = await UI.loadPSPDFKit(this.documentBytes, this.container, this.licenseKey, this.locale)
+        UI.addToolbarItems(this.pdfKit, this.handleClick.bind(this))
 
-        this.Instance.addEventListener(
+        this.pdfKit.addEventListener(
             'annotations.load',
             this.handleAnnotationsLoad.bind(this)
         )
-        this.Instance.addEventListener(
+        this.pdfKit.addEventListener(
             'annotations.change',
             this.handleAnnotationsChange.bind(this)
         )
-        this.Instance.addEventListener(
+        this.pdfKit.addEventListener(
             'annotations.create',
             this.handleAnnotationsCreate.bind(this)
         )
 
-        this.Instance.addEventListener("annotations.willChange", _ => {
+        this.pdfKit.addEventListener("annotations.willChange", _ => {
             Comp.ActPanel.Toggle();
         });
 
         // Load annotations into PSPDFKit
         try {
             this.signatureCount = this.currentDocument.elements.length
-            await createAnnotations(this.currentDocument, this.Instance)
+            await createAnnotations(this.currentDocument, this.pdfKit)
         } catch (e) {
             console.error("Error loading annotations:", e);
         }
@@ -96,7 +77,7 @@ class App {
 
             const request = await fetch(imageUrl)
             const blob = await request.blob()
-            const imageAttachmentId = await this.Instance.createAttachment(blob)
+            const imageAttachmentId = await this.pdfKit.createAttachment(blob)
 
             const frameAnnotation = createImageAnnotation(
                 new PSPDFKit.Geometry.Rect({
@@ -109,7 +90,7 @@ class App {
                 imageAttachmentId
             )
 
-            this.Instance.create(frameAnnotation)
+            this.pdfKit.create(frameAnnotation)
         }
     }
 
@@ -195,7 +176,7 @@ class App {
     }
 
     async handleFinish(event) {
-        const iJSON = await this.Instance.exportInstantJSON()
+        const iJSON = await this.pdfKit.exportInstantJSON()
         const iFormFieldValues = await iJSON.formFieldValues;
 
         //check required
@@ -249,7 +230,7 @@ class App {
                 //---
                 // Save changes before doing anything
                 try {
-                    await this.Instance.save()
+                    await this.pdfKit.save()
                 } catch (e) {
                     Swal.fire({
                         title: 'Fehler',
@@ -293,7 +274,7 @@ class App {
 
 
     async validateAnnotations(totalSignatures) {
-        const annotations = await getAnnotations(this.Instance)
+        const annotations = await getAnnotations(this.pdfKit)
         const filtered = annotations
             .map(a => a.toJS())
             .filter(a => a.isSignature)
@@ -314,7 +295,7 @@ class App {
         })
 
         if (result.isConfirmed) {
-            const result = await deleteAnnotations(this.Instance)
+            const result = await deleteAnnotations(this.pdfKit)
         }
 
         return result