get() returns blank image if metadata not loaded and no arguments
get() returns blank image if metadata not loaded and no arguments

`get()` return as `p5.Image` if no arguments are passed in.  For examples that are copying from a video element, this fix allows `get()` to return a blank image while waiting for the `loadedmetadata`
nucliweb/p5.js,johnpasquarello/p5.js,karenpeng/p5.js,dhowe/p5.js,kadamwhite/p5.js,Jared-Sprague/p5.js,Jared-Sprague/p5.js,indefinit/p5.js,processing/p5.js,mlarghydracept/p5.js,sakshamsaxena/p5.js,joecridge/p5.js,joecridge/p5.js,black-kite/p5.js,limzykenneth/p5.js,dhowe/p5.js,shiffman/p5.js,kadamwhite/p5.js,bomoko/p5.js,karenpeng/p5.js,kennethdmiller3/p5.js,indefinit/p5.js,limzykenneth/p5.js,mlarghydracept/p5.js,bomoko/p5.js,sakshamsaxena/p5.js,shiffman/p5.js,processing/p5.js,kennethdmiller3/p5.js,black-kite/p5.js,johnpasquarello/p5.js,nucliweb/p5.js