Update src/librustc_mir/interpret/place.rs

Co-Authored-By: Ralf Jung <post@ralfj.de>

Author: oli-obk

src/librustc_mir/interpret/place.rs

@@ -532,7 +532,7 @@ where
                 }
 
                 let index = if from_end {
-                    assert!(offset - 1 < min_length);
+                    assert!(0 < offset && offset - 1 < min_length);
                     n - u64::from(offset)
                 } else {
                     assert!(offset < min_length);