Fix NPE in MERGE USING with unknown column

h2/src/docsrc/html/changelog.html

@@ -21,6 +21,10 @@ Change Log
 
 <h2>Next Version (unreleased)</h2>
 <ul>
+<li>Issue #1490: NullPointerException when running invalid MERGE statement
+</li>
+<li>Issue #1488: Improve documentation of window and some other functions
+</li>
 <li>Issue #1485: Default window frame in presence of ORDER BY is RANGE .., not ROWS
 </li>
 <li>PR #1484: New tests, reimplemented EXCLUDE clause, and assorted changes

h2/src/main/org/h2/expression/ExpressionColumn.java

@@ -317,9 +317,15 @@ public class ExpressionColumn extends Expression {
             }
             return true;
         case ExpressionVisitor.GET_COLUMNS1:
+            if (column == null) {
+                throw DbException.get(ErrorCode.COLUMN_NOT_FOUND_1, getSQL());
+            }
             visitor.addColumn1(column);
             return true;
         case ExpressionVisitor.GET_COLUMNS2:
+            if (column == null) {
+                throw DbException.get(ErrorCode.COLUMN_NOT_FOUND_1, getSQL());
+            }
             visitor.addColumn2(column);
             return true;
         default:

h2/src/test/org/h2/test/scripts/dml/mergeUsing.sql

@@ -208,5 +208,8 @@ SELECT * FROM TEST;
 > 30
 > rows: 3
 
+MERGE INTO TEST USING (SELECT 40) ON UNKNOWN_COLUMN = 1 WHEN NOT MATCHED THEN INSERT (ID) VALUES (40);
+> exception COLUMN_NOT_FOUND_1
+
 DROP TABLE TEST;
 > ok