fix(memline): don't check line count for closed memline #32403

Problem:  Error thrown when for invalid line number which may be accessed
          in an `on_detach` callback at which point line count is
          intentionally set to 0.
Solution: Move empty memline check to before line number check.

1 files changed, 5 insertions, 5 deletions

diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index fb7fdfb8b2..047bbbfdaa 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -1875,6 +1875,11 @@ static char *ml_get_buf_impl(buf_T *buf, linenr_T lnum, bool will_change)
   static int recursive = 0;
   static char questions[4];
 
+  if (buf->b_ml.ml_mfp == NULL) {       // there are no lines
+    buf->b_ml.ml_line_len = 1;
+    return "";
+  }
+
   if (lnum > buf->b_ml.ml_line_count) {  // invalid line number
     if (recursive == 0) {
       // Avoid giving this message for a recursive call, may happen when
@@ -1892,11 +1897,6 @@ errorret:
   }
   lnum = MAX(lnum, 1);  // pretend line 0 is line 1
 
-  if (buf->b_ml.ml_mfp == NULL) {       // there are no lines
-    buf->b_ml.ml_line_len = 1;
-    return "";
-  }
-
   // See if it is the same line as requested last time.
   // Otherwise may need to flush last used line.
   // Don't use the last used line when 'swapfile' is reset, need to load all