vim-patch:9.1.0007: can select empty inner text blocks

Problem:  can select empty inner text blocks
          (laurentalacoque)
Solution: make selecting empty inner text blocks an error

textobjects: Make selecting inner empty blocks an error

fixes: vim/vim#13514
closes: vim/vim#13523

ad4d7f446d

Co-authored-by: Christian Brabandt <cb@256bit.org>

src/nvim/textobject.c

@@ -955,6 +955,12 @@ int current_block(oparg_T *oap, int count, bool include, int what, int other)
       }
     }
 
+    if (equalpos(start_pos, *end_pos)) {
+      // empty block like this: ()
+      // there is no inner block to select, abort
+      return FAIL;
+    }
+
     // In Visual mode, when the resulting area is not bigger than what we
     // started with, extend it to the next block, and then exclude again.
     // Don't try to expand the area if the area is empty.