fix crash on text deletion

src/core/file_buffer.odin

@@ -1081,7 +1081,9 @@ delete_content_from_buffer_cursor :: proc(buffer: ^FileBuffer, amount: int) {
                 iterate_file_buffer_reverse(&it);
 
                 if it.hit_end {
-                    runtime.ordered_remove(&buffer.content_slices, it.cursor.index.slice_index);
+                    if len(buffer.content_slices) > 1 {
+                        runtime.ordered_remove(&buffer.content_slices, it.cursor.index.slice_index);
+                    }
                 } else {
                     runtime.ordered_remove(&buffer.content_slices, it.cursor.index.slice_index+1);
                 }

src/pkg/grep_lib/src/lib.rs

@@ -1,17 +1,12 @@
 use std::{
     error::Error,
-    ffi::{CStr, CString, OsString},
-    path::Path,
-    str::FromStr,
-    sync::mpsc::{Receiver, Sender},
-    thread,
+    ffi::CStr,
 };
 
 use grep::{
     regex::RegexMatcherBuilder,
     searcher::{BinaryDetection, SearcherBuilder, Sink, SinkError},
 };
-use std::sync::mpsc::channel;
 use walkdir::WalkDir;
 
 #[derive(Debug)]

src/tests/tests.odin

@@ -246,6 +246,39 @@ insert_before_slice :: proc(t: ^testing.T) {
     testing.expectf(t, contents == expected_text, "got '%v', expected '%v'", contents, expected_text)
 }
 
+@(test)
+delete_last_content_slice_beginning_of_file :: proc(t: ^testing.T) {
+    e := new_test_editor()
+    setup_empty_buffer(&e)
+
+    buffer := &e.buffers[0]
+
+    run_text_insertion(&e, "Hello, world!")
+
+    // Delete just the text
+    run_input_multiple(&e, press_key(.I), 1)
+    run_input_multiple(&e, press_key(.BACKSPACE), 13)
+
+    expect_line_col(t, buffer.cursor, 0, 0)
+    expect_cursor_index(t, buffer.cursor, 0, 0)
+
+    // Try to delete when there is no text
+    run_input_multiple(&e, press_key(.BACKSPACE), 1)
+
+    expect_line_col(t, buffer.cursor, 0, 0)
+    expect_cursor_index(t, buffer.cursor, 0, 0)
+    testing.expect(t, len(buffer.content_slices) > 0, "BACKSPACE deleted final content slice in buffer")
+
+    // "commit" insert mode changes, then re-enter insert mode and try to delete again
+    run_input_multiple(&e, press_key(.ESCAPE), 1)
+    run_input_multiple(&e, press_key(.I), 1)
+    run_input_multiple(&e, press_key(.BACKSPACE), 1)
+
+    expect_line_col(t, buffer.cursor, 0, 0)
+    expect_cursor_index(t, buffer.cursor, 0, 0)
+    testing.expect(t, len(buffer.content_slices) > 0, "BACKSPACE deleted final content slice in buffer")
+}
+
 @(test)
 delete_in_slice :: proc(t: ^testing.T) {
     e := new_test_editor()