From 4fa1cc83d9aeceddc7f9bed75edf788e95e9d60c Mon Sep 17 00:00:00 2001
From: Terence Parr <parrt@antlr.org>
Date: Sat, 21 May 2022 11:15:00 -0700
Subject: [PATCH] Fixes #555.  Guard against null ptr

Signed-off-by: Terence Parr <parrt@antlr.org>
---
 src/main/java/org/antlr/intellij/plugin/preview/InputPanel.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/antlr/intellij/plugin/preview/InputPanel.java b/src/main/java/org/antlr/intellij/plugin/preview/InputPanel.java
index 92e7f025..cd478766 100644
--- a/src/main/java/org/antlr/intellij/plugin/preview/InputPanel.java
+++ b/src/main/java/org/antlr/intellij/plugin/preview/InputPanel.java
@@ -234,7 +234,7 @@ public void documentChanged(DocumentEvent event) {
 
 	public void grammarFileSaved() {
 		clearParseErrors();
-		if ( previewState.startRuleName!=null ) {
+		if ( previewState!=null && previewState.startRuleName!=null ) {
 			setStartRuleName(previewState.grammarFile, previewState.startRuleName);
 		}
 		else {