diff --git a/abstract/ActivityBlock.js b/abstract/ActivityBlock.js
index 929711a54..b1f5ad56d 100644
--- a/abstract/ActivityBlock.js
+++ b/abstract/ActivityBlock.js
@@ -191,7 +191,6 @@ export class ActivityBlock extends Block {
   }
 }
 
-/** @enum {String} */
 ActivityBlock.activities = Object.freeze({
   START_FROM: 'start-from',
   CAMERA: 'camera',
diff --git a/abstract/Block.js b/abstract/Block.js
index fb3e293c4..ff553b4df 100644
--- a/abstract/Block.js
+++ b/abstract/Block.js
@@ -20,6 +20,8 @@ export class Block extends BaseComponent {
   static className = '';
   requireCtxName = false;
   allowCustomTemplate = true;
+  /** @type {import('./ActivityBlock.js').ActivityType} */
+  activityType = null;
 
   init$ = blockCtx();
 
@@ -57,8 +59,6 @@ export class Block extends BaseComponent {
 
   constructor() {
     super();
-    /** @type {import('./ActivityBlock.js').ActivityType} */
-    this.activityType = null;
     // @ts-ignore TODO: fix this
     this.addTemplateProcessor(l10nProcessor);
     // TODO: inspect template on lr-* elements
diff --git a/abstract/UploaderBlock.js b/abstract/UploaderBlock.js
index c839f1b6d..f66e474ea 100644
--- a/abstract/UploaderBlock.js
+++ b/abstract/UploaderBlock.js
@@ -408,22 +408,35 @@ export class UploaderBlock extends ActivityBlock {
    * @param {import('./TypedData.js').TypedData} [internalEntry]
    */
   _validateUploadError(outputEntry, internalEntry) {
-    /** @type {Error} */
-    const error = internalEntry?.getValue('uploadError');
-    if (!error) {
+    /** @type {unknown} */
+    const cause = internalEntry?.getValue('uploadError');
+    if (!cause) {
       return;
     }
 
-    /** @type {import('../types').OutputFileErrorType} */
-    const errorType =
-      error instanceof UploadError ? 'UPLOAD_ERROR' : error instanceof NetworkError ? 'NETWORK_ERROR' : 'UNKNOWN_ERROR';
-
-    return buildOutputFileError({
-      type: errorType,
-      entry: outputEntry,
-      message: error.message,
-      error,
-    });
+    if (cause instanceof UploadError) {
+      return buildOutputFileError({
+        type: 'UPLOAD_ERROR',
+        message: cause.message,
+        entry: outputEntry,
+        error: cause,
+      });
+    } else if (cause instanceof NetworkError) {
+      return buildOutputFileError({
+        type: 'NETWORK_ERROR',
+        message: cause.message,
+        entry: outputEntry,
+        error: cause,
+      });
+    } else {
+      const error = cause instanceof Error ? cause : new Error('Unknown error', { cause });
+      return buildOutputFileError({
+        type: 'UNKNOWN_ERROR',
+        message: error.message,
+        entry: outputEntry,
+        error,
+      });
+    }
   }
 
   /**
diff --git a/blocks/StartFrom/StartFrom.js b/blocks/StartFrom/StartFrom.js
index 05d2e37a0..18ac4a098 100644
--- a/blocks/StartFrom/StartFrom.js
+++ b/blocks/StartFrom/StartFrom.js
@@ -2,6 +2,7 @@ import { ActivityBlock } from '../../abstract/ActivityBlock.js';
 
 export class StartFrom extends ActivityBlock {
   historyTracked = true;
+  /** @type {import('../../abstract/ActivityBlock.js').ActivityType} */
   activityType = 'start-from';
 
   initCallback() {
diff --git a/types/exported.d.ts b/types/exported.d.ts
index d6cc74e36..1a50d1081 100644
--- a/types/exported.d.ts
+++ b/types/exported.d.ts
@@ -1,5 +1,7 @@
-import { UploadcareFile, UploadClientError, UploadcareNetworkError, UploadcareGroup } from '@uploadcare/upload-client';
-
+export type UploadError = import('@uploadcare/upload-client').UploadError;
+export type UploadcareFile = import('@uploadcare/upload-client').UploadcareFile;
+export type NetworkError = import('@uploadcare/upload-client').NetworkError;
+export type UploadcareGroup = import('@uploadcare/upload-client').UploadcareGroup;
 export type Metadata = import('@uploadcare/upload-client').Metadata;
 export type MetadataCallback = (fileEntry: OutputFileEntry) => Promise<Metadata> | Metadata;
 export type ConfigType = {
@@ -89,10 +91,10 @@ export type OutputErrorTypePayload = {
     total: number;
   };
   UPLOAD_ERROR: OutputFileErrorPayload & {
-    error: UploadClientError;
+    error: UploadError;
   };
   NETWORK_ERROR: OutputFileErrorPayload & {
-    error: UploadcareNetworkError;
+    error: NetworkError;
   };
   UNKNOWN_ERROR: OutputFileErrorPayload & {
     error?: Error;
diff --git a/types/jsx.d.ts b/types/jsx.d.ts
index b14a2c041..3e3d9689b 100644
--- a/types/jsx.d.ts
+++ b/types/jsx.d.ts
@@ -61,7 +61,7 @@ declare namespace JSX {
       CloudImageEditorBlock,
       JSX.IntrinsicElements['lr-cloud-image-editor-block'] & ShadowWrapperAttributes
     >;
-    'lr-form-input': CustomElement<InstanceType<DataOutput>, CtxAttributes>;
+    'lr-form-input': CustomElement<FormInput, CtxAttributes>;
     'lr-file-uploader-regular': CustomElement<FileUploaderRegular, CtxAttributes & ShadowWrapperAttributes>;
     'lr-file-uploader-minimal': CustomElement<FileUploaderMinimal, CtxAttributes & ShadowWrapperAttributes>;
     'lr-file-uploader-inline': CustomElement<FileUploaderInline, CtxAttributes & ShadowWrapperAttributes>;