perl, 81 bytes

Result

ERROR

Code [DL]

$_=`dd`;m/^ *K/m;s/^ {@{[(length$&)-1]}}\K /#/mg;s/# *(?=T)/"#"x length$&/e;print

stdin

                                 T                
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                          K                       

stdout

stderr

strace