Fix kill-selection crash when selection start is out-of-bounds

This part of the code could use some love; when we happen to clear the
selected text, we should end the selection.

But that's not how it works today. This is fine for Vi mode, because Vi
mode never deletes in visual mode.

Let's fix the crash for now.

Fixes #11367

(cherry picked from commit af3b49bf9c)

src/reader.rs

@@ -3705,8 +3705,11 @@ fn clear_pager(&mut self) {
 
     fn get_selection(&self) -> Option<Range<usize>> {
         let selection = self.selection?;
-        let start = selection.start;
+        let start = std::cmp::min(selection.start, self.command_line.len());
         let end = std::cmp::min(selection.stop, self.command_line.len());
+        if start == end {
+            return None;
+        }
         Some(start..end)
     }
 

tests/pexpects/bind.py

@@ -28,6 +28,21 @@ expect_prompt(increment=False)
 send("\f")
 expect_prompt(increment=False)
 
+# Test that kill-selection after selection is cleared doesn't crash
+sendline("bind ctrl-space begin-selection")
+expect_prompt()
+sendline("bind ctrl-w kill-selection end-selection")
+expect_prompt()
+send("echo 123")
+# Send Ctrl-Space using CSI u encoding
+send("\x1b[32;5u")
+# Send Ctrl-C to clear the command line
+send("\x1b[99;5u")
+# Send Ctrl-W which used to crash
+send("\x1b[119;5u")
+sendline("bind --erase ctrl-space ctrl-w")
+expect_prompt()
+
 # Fish should start in default-mode (i.e., emacs) bindings. The default escape
 # timeout is 30ms.
 #