I was testing my new workflow code that synchronizes the UI to the machine state and I ran across the following problem. One of my tests involved erroneous GCode; I wanted to ensure that errors were handled in program order. The erroneous GCode line was:

messed up 

The dataFilter treated that as if it contained the GCode word "M0" and paused the workflow!
I traced the problem down to parser.parseLine(), which returned the following words[] array from that line:

[ 'M0', 'E0', 'S0', 'S0', 'E0', 'D0', 'U0', 'P0' ] 

I believe that a valid GCode word must be a letter followed by a real number, hence there are no valid GCode words in "messed up", so the correct result should be the empty array.

I think the root cause of the problem is in the following regular expression in gcode-parser:parseLine():

const re = /(%.*)|({.*)|((?:\$\$)|(?:\$[a-zA-Z0-9#]*))|([a-zA-Z][0-9\+\-\.]*)|(\*[0-9]+)/igm; 

which should instead be

const re = /(%.*)|({.*)|((?:\$\$)|(?:\$[a-zA-Z0-9#]*))|([a-zA-Z][0-9\+\-\.]+)|(\*[0-9]+)/igm; 

I.e. the subexpression [0-9\+\-\.] should be followed by +, not *, so the numeric suffix is mandatory.

After making this change, my synchronized workflow code behaved properly.