MVStore: improved error message

h2/src/main/org/h2/mvstore/Page.java

@@ -166,13 +166,17 @@ public class Page {
             long pos, long filePos, long fileSize) {
         ByteBuffer buff;
         int maxLength = DataUtils.getPageMaxLength(pos);
-        maxLength = (int) Math.min(fileSize - filePos, maxLength);
-        int length = maxLength;
         if (maxLength == Integer.MAX_VALUE) {
             buff = fileStore.readFully(filePos, 128);
             maxLength = buff.getInt();
             // read the first bytes again
         }
+        maxLength = (int) Math.min(fileSize - filePos, maxLength);
+        int length = maxLength;
+        if (length < 0) {
+            throw DataUtils.newIllegalStateException(DataUtils.ERROR_FILE_CORRUPT, 
+                    "Illegal page length {0} reading at {1}; file size {1} ", length, filePos, fileSize);
+        }
         buff = fileStore.readFully(filePos, length);
         Page p = new Page(map, 0);
         p.pos = pos;