woof-url.js

              if (error.url === "") {
                var emptyURLTypes = ["setBackdropURL('')", 'setBackdropURL("")', 'url: ""', "url: ''"]
                var emptyURLType = emptyURLTypes.find(t => code.includes(t))
                if (emptyURLType) {
                  app.error = {message: "You forgot to include an image or background URL.", lineno: code.substring(0, code.indexOf(emptyURLType)).split('\n').length}
                } else {
                  // We can't figure out the lineno if it's set to an empty string variable
                  // https://woofjs.com/create#image-url-issue
                  app.error = {message: "You forgot to include an image or background URL.", lineno: null}
                }
              } else {
              app.error = {message: "Your image URL (" + error.url +") is misspelled or not correct.", lineno: code.substring(0, code.indexOf(error.url)).split('\n').length}
              }