Javascript compatibility found with IE11 in this plugin

In js/deprecation-notice.js:

function reportDeprecation( message ) {
		// Do not write to the logfile if this is the backend and the notices are written to the screen.
		if ( JQMH.backend && notice.length ) {
			return;
		}

		if ( ! JQMH.capture_deprecations ) {
			return;
		}

		let data = {
			action: 'jquery-migrate-log-notice',
			notice: message,
			nonce: JQMH.report_nonce,
			backend: JQMH.backend,
			url: window.location.href,
		};

		$.post( {
			url: JQMH.ajaxurl,
			data
		} );
	}

tail codes should be (supplement missing name for data)

		$.post( {
			url: JQMH.ajaxurl,
			data: data
		} );

or ( use two args style )

		$.post( 
			JQMH.ajaxurl,
			data
		);

In class-jquery-migrate-helper.php:

				var match_pattern = /\)\.(.+?) is not a function/;
                var erroredFunction = msg.match( match_pattern );

                // If there was no matching functions, do not try to downgrade.
                if ( typeof erroredFunction !== 'object' || typeof erroredFunction[1] === "undefined" || -1 === jQueryFunctions.indexOf( erroredFunction[1] ) ) {
                    return true;
                }

erroredFunction === null should be checked first, or erroredFunction is null if no matches, following condition check may not worked as expected, null is object, maybe unable to refer erroredFunction[1].

Above issues are found with IE11, but may affect to others.