Fix a couple display glitches; preserve completions

racket-pdb.el

@@ -250,6 +250,7 @@ this mode."
 (defvar-local racket--pdb-errors-index -1)
 
 (defun racket--pdb-reset-errors (errors)
+  (racket--remove-face-overlays-in-buffer racket-xp-error-face)
   (let ((errors (sort errors (lambda (a b) (< (car a) (car b))))))
     (dolist (e errors)
       (pcase-let ((`(,beg ,end . ,_) e))
@@ -364,7 +365,9 @@ This is ad hoc and forensic."
          (pcase response
            (`((completions . ,completions)
               (errors      . ,errors))
-            (setq racket--xp-binding-completions completions) ;racket-xp-complete.el
+            (racket--pdb-remove-all-face-overlays)
+            (when completions ;if none b/c e.g. error, retain old ones
+              (setq racket--xp-binding-completions completions)) ;racket-xp-complete.el
             (racket--pdb-reset-errors errors)
             (racket--pdb-set-status (if errors 'err 'ok))
             (racket--pdb-show-after-motion))))))))