FYI, kept hitting this stacktrace in the demo: TypeError: Cannot read property 'key' of undefined at a.n.renderBlockButton (https://www.slatejs.org/main-17

FYI, kept hitting this stacktrace in the demo: TypeError: Cannot read property 'key' of undefined at a.n.renderBlockButton (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:42:22776 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:42:2277...) at a.value (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:42:25055 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:42:2505...) at Mi (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:62668 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:6266...) at Ti (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:67552 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:6755...) at mo (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:77129 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:7712...) at fo (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:77436 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:7743...) at Zo (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:80984 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:8098...) at Vo (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:80496 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:8049...) at Wo (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:80322 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:8032...) at Io (https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:79695 https://www.slatejs.org/main-1783ad63c9cf9b77dd4d.js:22:7969...) in a in a in a in div in Styled(div) in div in a in a in a