[geary: 17/23] Check if header exists before reading value

[Michael Gratton <mjog src gnome org>]

commit 4677f4fe4a9066bd31f057095da01fbebb2e4fcc
Author: Torben <torben letorbi gmail com>
Date:   Mon Dec 16 14:39:43 2019 +0100

    Check if header exists before reading value

 src/engine/rfc822/rfc822-message-data.vala | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/src/engine/rfc822/rfc822-message-data.vala b/src/engine/rfc822/rfc822-message-data.vala
index 814e071c..bd7dda7c 100644
--- a/src/engine/rfc822/rfc822-message-data.vala
+++ b/src/engine/rfc822/rfc822-message-data.vala
@@ -323,7 +323,11 @@ public class Geary.RFC822.Header : Geary.MessageData.BlockMessageData, Geary.RFC
     }
 
     public string? get_header(string name) throws RFC822Error {
-        return GMime.utils_header_unfold(get_headers().get_header(name).get_raw_value());
+        GMime.Header header = get_headers().get_header(name);
+        if (header != null)
+            return GMime.utils_header_unfold(header.get_raw_value());
+        else
+            return null;
     }
 
     public string[] get_header_names() throws RFC822Error {