Clear previous error message

src/App.vue

@@ -52,12 +52,16 @@ export default {
     submitStatement() {
       // Handle submission logic and render proof tree
 
+      // Clear previous error message
+      this.errorMsg = '';
+
       // Catch parsing error messages
       try {
         const targetAst = parse(this.givenStatement);
         this.latexStatement = ast.astsToLateX(targetAst);
         this.proofTree = new sequentNode(this.latexStatement);
         this.renderProofTree();
+        
       } catch (error) {
         this.errorMsg = 'Parsing error: ' + error.message;
         // Handle the error here, such as displaying an error message to the user