one of those moments of programming eloquence you hope for, discovered to be unneeded immediately upon finishing it
the final code:
handleWordClick = (word, event) => {
let isShiftClick = (this.state.shiftActive);
let [ hasClickFn , hasShiftClickFn ] = [ 'onClick', 'onShiftClick' ].map((p) => (typeof this.props[p] === 'function'));