fix: prevent KeymanWeb load of keyboards that do not have .js versions#1821

mcdurdin merged 1 commit intomasterkeymanapp/help.keyman.com:masterfrom

fix/13043-handle-errors-loading-keyboards-and-dont-load-non-js-keyboardskeymanapp/help.keyman.com:fix/13043-handle-errors-loading-keyboards-and-dont-load-non-js-keyboardsCopy head branch name to clipboard