mu4e-view: fallback to raw view for unreadable messages

So users can at least see _something_...

mu4e/mu4e-view.el

@@ -134,7 +134,7 @@ Then, display the results."
                      ((mu4e-current-buffer-type-p 'view)
                       (when (mu4e--view-detached-p (current-buffer))
                         (mu4e-error
-                         "Cannot navigate in a detached view buffer."))
+                         "Cannot navigate in a detached view buffer"))
                       (mu4e-get-headers-buffer))
                      ;; fallback; but what would trigger this?
                      (t (mu4e-get-headers-buffer))))
@@ -235,9 +235,10 @@ If this succeeds, return the new docid. Otherwise, return nil."
 ;;; Interactive functions
 (defun mu4e-view-action (&optional msg)
   "Ask user for some action to apply on MSG, then do it.
-If MSG is nil apply action to message returned
-bymessage-at-point.  The actions are specified in
-`mu4e-view-actions'."
+If MSG is nil apply action to message returned by
+`mu4e-message-at-point'.
+
+ The actions are specified in `mu4e-view-actions'."
   (interactive)
   (let* ((msg (or msg (mu4e-message-at-point)))
          (actionfunc (mu4e-read-option "Action: " mu4e-view-actions)))
@@ -327,7 +328,7 @@ Add this function to `mu4e-view-mode-hook' to enable this feature."
   "Detach the view buffer from its headers buffer."
   (interactive)
   (unless mu4e-linked-headers-buffer
-    (mu4e-error "This view buffer is already detached."))
+    (mu4e-error "This view buffer is already detached"))
   (mu4e-message "Detached view buffer from %s"
                 (progn mu4e-linked-headers-buffer
                   (with-current-buffer mu4e-linked-headers-buffer
@@ -339,7 +340,7 @@ Add this function to `mu4e-view-mode-hook' to enable this feature."
                   (rename-buffer (make-temp-name (buffer-name)) t))))
 
 (defun mu4e-view-attach (headers-buffer)
-  "Attaches a view buffer to a headers buffer."
+  "Attaches a view buffer to HEADERS-BUFFER."
   (interactive
    (list (get-buffer (read-buffer
                       "Select a headers buffer to attach to: " nil t
@@ -422,7 +423,6 @@ list."
   (mu4e--view-in-headers-context
    (mu4e-mark-execute-all)))
 
-
 ;;; URL handling
 
 (defvar mu4e--view-link-map nil
@@ -640,7 +640,8 @@ As a side-effect, a message that is being viewed loses its
         ;; problems later (#2260, #2508), so let's remove those
         (article-remove-cr)
         (setq-local mu4e--view-message msg)
-        (mu4e--view-render-buffer msg))
+        (ignore-errors
+          (mu4e--view-render-buffer msg)))
       (mu4e-loading-mode 0)))
   (unless (mu4e--view-detached-p gnus-article-buffer)
     (with-current-buffer mu4e-linked-headers-buffer
@@ -741,8 +742,9 @@ determine which browser function to use."
           (set-buffer-modified-p nil)
           (add-hook 'kill-buffer-hook #'mu4e--view-kill-mime-handles))
       (epg-error
-       (mu4e-warn "EPG error: %s; fall back to raw view"
-                  (error-message-string err))))))
+       (mu4e-message "EPG error: %s; fall back to raw view"
+                  (error-message-string err))
+       (error)))))
 
 (defun mu4e-view-refresh ()
   "Refresh the message view."