Freron MailMate

I'm developing a bundle that inserts text into email messages in the Composer window. I'm adding an action to the output to change the subject.

To recreate the bug: open a new composer window, invoke the command which returns an action to changeHeaders. The first time this happens, the header does not change (at least, the new header is not displayed in the composer window). Invoke the command a second time, and MailMate crashes.

Here is the output from running this (with my email address removed).

% /Applications/MailMate.app/Contents/MacOS/MailMate                                                                                                                                            8:35:55
Note: Message reference cycle encountered (421314)
Note: Message reference cycle encountered (473500)
Warning: MmDefaultBccHeader is not a string value.
Triggered event inline_css with 1 bundle commands (part: -1, input size: 1319, opts: kAsynchronousAllowed)
Note: Generating message with 1 async operations missing
 Async final result (time: 0.104000, valid: 1, output size: 312)
Triggered event inline_css with 1 bundle commands (part: -1, input size: 1319, opts: kAsynchronousAllowed)
 Cached result found (time: 0.000000, output size: 312)
Triggered command named “ Insert text template”
Input type is “none”
Triggered command named “ Insert text template” for single message (2578849)
 Time elapsed: 0.951000 ( Insert text template)

Raw output from command:
{
  "actions" : [
    {
      "type" : "changeHeaders",
      "headers" : {
        "subject" : "New Subject"
      }
    }
  ]
}


Parsed output from command:
{   actions = (
        {   headers = { subject = "New Subject"; };
            type = "changeHeaders";
        },
    );
}

Final result:
{   actions = (
        {   headers = { subject = "New Subject"; };
            ids = ( 2578849 );
            type = "changeHeaders";
        },
    );
}
Triggered command named “ Insert text template”
Input type is “none”
Triggered command named “ Insert text template” for single message (2578849)
 Time elapsed: 0.994000 ( Insert text template)

Raw output from command:
{
  "actions" : [
    {
      "type" : "changeHeaders",
      "headers" : {
        "subject" : "New Subject"
      }
    }
  ]
}


Parsed output from command:
{   actions = (
        {   headers = { subject = "New Subject"; };
            type = "changeHeaders";
        },
    );
}

Final result:
{   actions = (
        {   headers = { subject = "New Subject"; };
            ids = ( 2578849 );
            type = "changeHeaders";
        },
    );
}
Unique ID: 2578849 (0x13d63d1f0):
Marked to be signed: 0
Has changed: 1
Has saved id: 1
Headers (0x0, 10):
                          #date: "2025-08-24 08:39:13 -0400"
                 #date-received: "2025-08-24 12:39:13"
                     #date-sent: "2025-08-24 12:39:13"
                   content-type: "multipart/alternative; boundary="=_MailMate_47754593-EA5E-4FDA-8370-F59FB2BC69BB_=""
                           date: "Sun, 24 Aug 2025 08:39:13 -0400"
                           from: "Stephen Chong <____@_______>"
                     message-id: "<42AC315B-4E1A-43EC-916B-3A2ECC43302A@_____>"
                   mime-version: "1.0"
                        subject: "New Subject"
                       x-mailer: "MailMate (2.0r6265)"
Updated headers: original-subject subject
Pointers (0x0,0x0,0x0):
Decoded size: 0
Number of subparts: 0
Fatal: Not decoded and no pointers available.
0x0,0x0,0x0
[1]    30022 abort      /Applications/MailMate.app/Contents/MacOS/MailMate