Fix issue when style prop is not an expression

Author: sstur

lib/rules/no-single-element-style-arrays.js

@@ -37,6 +37,7 @@ module.exports = {
     return {
       JSXAttribute(node) {
         if (node.name.name !== 'style') return;
+        if (!node.value.expression) return;
         if (node.value.expression.type !== 'ArrayExpression') return;
         if (node.value.expression.elements.length === 1) {
           reportNode(node);