Ignore errors when checking for object initializers (bug#63379)

Since this is merely a check for syntax, we don't really care about
any internal errors inside of backward-up-list.

* lisp/progmodes/csharp-mode.el (csharp-guess-basic-syntax): Wrap
command in ignore-errors.

lisp/progmodes/csharp-mode.el

@@ -493,7 +493,7 @@ compilation and evaluation time conflicts."
        ;; Next non-whitespace character should be '{'
        (goto-char (c-point 'boi))
        (unless (eq (char-after) ?{)
-         (backward-up-list 1 t t))
+         (ignore-errors (backward-up-list 1 t t)))
        (save-excursion
          ;; 'new' should be part of the line
          (goto-char (c-point 'iopl))