fix: null check

Author: barelyhuman

lib/plugin.js

@@ -409,6 +409,7 @@ function isFunctionIsland(functionAST) {
     },
     JSXAttribute(node) {
       if (
+        node.value &&
         node.value.type === 'JSXExpressionContainer' &&
         (node.value.expression.type === 'ArrowFunctionExpression' ||
           (node.value.expression.type == 'Identifier' &&