diff --git a/.changeset/itchy-snails-exist.md b/.changeset/itchy-snails-exist.md
new file mode 100644
index 0000000..6ab3f10
--- /dev/null
+++ b/.changeset/itchy-snails-exist.md
@@ -0,0 +1,5 @@
+---
+"sh-syntax": patch
+---
+
+fix: do not panic, return the error instead
diff --git a/main.go b/main.go
index ca5b7b1..e751a95 100644
--- a/main.go
+++ b/main.go
@@ -5,7 +5,6 @@ package main
 
 import (
 	"container/list"
-	"fmt"
 
 	"github.com/mailru/easyjson"
 	"github.com/rx-ts/sh-syntax/processor"
@@ -117,8 +116,7 @@ func process(
 	bytes, err := easyjson.Marshal(&result)
 
 	if err != nil {
-		fmt.Println(err)
-		panic(err)
+		bytes = []byte(err.Error())
 	}
 
 	return &bytes[0]
diff --git a/main.wasm b/main.wasm
index f038282..023dfeb 100755
Binary files a/main.wasm and b/main.wasm differ
diff --git a/src/processor.ts b/src/processor.ts
index 6633bda..ceef077 100644
--- a/src/processor.ts
+++ b/src/processor.ts
@@ -1,10 +1,10 @@
 import { IParseError, File, ShOptions, LangVariant } from './types.js'
 
 export class ParseError extends Error implements IParseError {
-  Filename: string
+  Filename?: string
   Incomplete: boolean
   Text: string
-  Pos: {
+  Pos?: {
     Col: number
     Line: number
     Offset: number
@@ -39,7 +39,7 @@ export const getProcessor = (
       originalText: string
     },
   ): Promise<string>
-
+  // eslint-disable-next-line sonarjs/cognitive-complexity
   async function processor(
     textOrAst: File | string,
     {
@@ -168,6 +168,15 @@ export const getProcessor = (
 
     const string = decoder.decode(result.subarray(0, end))
 
+    // naive check whether the string is a json
+    if (!string.startsWith('{"') && !string.endsWith('}')) {
+      throw new ParseError({
+        Filename: filepath,
+        Incomplete: true,
+        Text: string,
+      })
+    }
+
     const {
       file,
       text: processedText,
diff --git a/src/types.ts b/src/types.ts
index 3f49a51..e0abe43 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -85,8 +85,8 @@ export interface File extends Node {
 }
 
 export interface IParseError {
-  Filename: string
+  Filename?: string
   Incomplete: boolean
   Text: string
-  Pos: Pos
+  Pos?: Pos
 }