Header button continuously adds newlines

[cmrd-senya]

When I consequently push H button it adds and removes ### on the same line (toggles the heading) but it always adds a newline after the header. On removing of ### it doesn't delete the newline, so pressing the H button continuosly with the same line makes the text area filled with newlines. Expected behaviour: remove the extra newline if there is one after the header line when H is pressed for heading removal.