Merge pull request 'fix: add file existence check before save. Fix Bu…

…g 69948' (#2) from fix/java-check-file-exist into release/v1.10.0

Reviewed-on: https://git.onlyoffice.com/ONLYOFFICE/document-server-integration/pulls/2

web/documentserver-example/java/src/main/java/helpers/TrackManager.java

@@ -192,8 +192,12 @@ public static void processSave(final JSONObject body,
             ver.mkdirs();
         }
 
-        // get the path to the previous file version and rename the last file version with it
-        lastVersion.renameTo(new File(versionDir + File.separator + "prev." + curExt));
+        if (lastVersion.exists()) {
+            // get the path to the previous file version and rename the last file version with it
+            lastVersion.renameTo(new File(versionDir + File.separator + "prev." + curExt));
+        } else {
+            throw new Exception("The file not exist: " + lastVersion.getAbsolutePath());
+        }
 
         saveFile(byteArrayFile, toSave); // save document file