fix: don't allow empty drawings to be uploaded

crates/core/src/database/questions.rs

@@ -415,6 +415,9 @@ impl DataManager {
             // this is the initial iter to check sizes, we'll do uploads after
             if drawing.len() > Self::MAXIMUM_DRAWING_SIZE {
                 return Err(Error::FileTooLarge);
+            } else if drawing.len() < 25 {
+                // if we have less than 25 bytes in a drawing, the drawing is likely blank
+                return Err(Error::FileTooSmall);
             }
         }