small fix

Author: qunaibit

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/compiler/SourceMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * The Universal Permissive License (UPL), Version 1.0
@@ -198,6 +198,9 @@ public void appendLocation(int startLine, int startColumn, int endLine, int endC
             if (endLine == 0) {
                 endLine = startLine;
             }
+            if (endColumn == 0) {
+                endColumn = startColumn;
+            }
             assert startLine >= 0 && endLine >= startLine && (startLine != endLine || endColumn >= startColumn);
             int lineDelta = startLine - lastLine;
             int lineSpan = endLine - startLine;