mu4e: work-around for format-flowed corner-case

Fixes: #1938
(fixes, eh, works around it)

mu4e/mu4e-compose.el

@@ -459,6 +459,7 @@ separated by blank lines. If variable `use-hard-newlines' is not
 set, this simply executes `fill-paragraph'."
   ;; Inspired by https://www.emacswiki.org/emacs/UnfillParagraph
   (interactive (progn (barf-if-buffer-read-only) '(t)))
+  (ignore-errors
     (if mu4e-compose-format-flowed
         (let ((fill-column (point-max))
               (use-hard-newlines nil)); rfill "across" hard newlines
@@ -467,7 +468,7 @@ set, this simply executes `fill-paragraph'."
           (fill-paragraph nil region))
       (when (use-region-p)
         (delete-trailing-whitespace (region-beginning) (region-end)))
-    (fill-paragraph nil region)))
+      (fill-paragraph nil region))))
 
 (defun mu4e-toggle-use-hard-newlines ()
   (interactive)