fix(gridstore-downloadstream): In gridstore download stream ensure that start is never bigger than end ZMS-235 (#828)

* in gridstore download stream ensure that start is never bigger than end

* refactor if statements

Author: NickOvt

lib/attachments/gridstore-storage.js

@@ -366,12 +366,23 @@ class GridstoreStorage {
                 }
             }
 
-            if (streamOptions.start && streamOptions.start > attachmentData.length) {
-                streamOptions.start = attachmentData.length;
-            }
+            streamOptions.start = Math.min(
+                streamOptions.start ?? 0, // Default to 0 if undefined/null
+                attachmentData.length
+            );
 
-            if (streamOptions.end && streamOptions.end > attachmentData.length) {
+            streamOptions.end = Math.min(
+                streamOptions.end ?? attachmentData.length, // Default to length if undefined/null
+                attachmentData.length
+            );
+
+            if (streamOptions.start >= attachmentData.length) {
+                // If start is at or beyond EOF, set both to EOF
+                streamOptions.start = attachmentData.length;
                 streamOptions.end = attachmentData.length;
+            } else if (streamOptions.start >= streamOptions.end) {
+                // If start >= end, clamp start to end (but not beyond file length)
+                streamOptions.start = Math.min(streamOptions.end, attachmentData.length);
             }
         }