thunderbird 91.6 wont open unknown attachments

The latest thunderbird won't open attachments with an unknown extension, I have an email with an attachment named 10222.set, double click does nothing, same with a right click and open. no application is associated with the .set extension, if I associate notepad++ same problem occurs. if i save the extension to disk, opens correctly. V95 onwards does seem to have a lot of bugs with extension handling. error console reports this: Uncaught (in promise) Exception { name: "NS_ERROR_NOT_AVAILABLE", message: "Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsIMIMEService.getFromTypeAndExtension]", result: 2147746065, filename: "chrome://messenger/content/msgHdrView.js", lineNumber: 1980, columnNumber: 0, data: null, stack: "open@chrome://messenger/content/msgHdrView.js:1980:35\n", location: XPCWrappedNative_NoHelper } ​ columnNumber: 0 ​ data: null ​ filename: "chrome://messenger/content/msgHdrView.js" ​ lineNumber: 1980 ​ location: XPCWrappedNative_NoHelper { QueryInterface: QueryInterface(), filename: Getter, name: Getter, … } ​​ QueryInterface: function QueryInterface() ​​ asyncCaller: null ​​ asyncCause: null ​​ caller: null ​​ columnNumber: 35 ​​ filename: "chrome://messenger/content/msgHdrView.js" ​​ formattedStack: "open@chrome://messenger/content/msgHdrView.js:1980:35\n" ​​ lineNumber: 1980 ​​ name: "open" ​​ nativeSavedFrame: SavedFrame { source: "chrome://messenger/content/msgHdrView.js", sourceId: 218, line: 1980, … } ​​ sourceId: 218 ​​ sourceLine: "" ​​ toString: function toString() ​​ <get asyncCaller()>: function asyncCaller() ​​ <get asyncCause()>: function asyncCause() ​​ <get caller()>: function caller() ​​ <get columnNumber()>: function columnNumber() ​​ <get filename()>: function filename() ​​ <get formattedStack()>: function formattedStack() ​​ <get lineNumber()>: function lineNumber() ​​ <get name()>: function name() ​​ <get nativeSavedFrame()>: function nativeSavedFrame() ​​ <get sourceId()>: function sourceId() ​​ <get sourceLine()>: function sourceLine() ​​ <prototype>: Object { … } ​ message: "Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsIMIMEService.getFromTypeAndExtension]" ​ name: "NS_ERROR_NOT_AVAILABLE" ​ result: 2147746065 ​ stack: "open@chrome://messenger/content/msgHdrView.js:1980:35\n" ​ <prototype>: ExceptionPrototype { toString: toString(), name: Getter, message: Getter, … }