debugger: Fix inline values panic when selecting stack frames (#30821)

Release Notes:

- debugger beta: Fix panic that could occur when selecting a stack frame
- debugger beta: Fix inline values not showing in stack trace view

Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>
Co-authored-by: Remco Smits <djsmits12@gmail.com>

.zed/debug.json

@@ -2,16 +2,14 @@
   {
     "label": "Debug Zed (CodeLLDB)",
     "adapter": "CodeLLDB",
-    "program": "$ZED_WORKTREE_ROOT/target/debug/zed",
-    "request": "launch",
-    "cwd": "$ZED_WORKTREE_ROOT"
+    "program": "target/debug/zed",
+    "request": "launch"
   },
   {
     "label": "Debug Zed (GDB)",
     "adapter": "GDB",
-    "program": "$ZED_WORKTREE_ROOT/target/debug/zed",
+    "program": "target/debug/zed",
     "request": "launch",
-    "cwd": "$ZED_WORKTREE_ROOT",
     "initialize_args": {
       "stopAtBeginningOfMainSubprogram": true
     }