Add styleJSONseemsValid function

js/sections-util.js

@@ -96,3 +96,14 @@ function calcStyleDigest(style) {
     return parts.join('');
   }
 }
+
+function styleJSONseemsValid(json) {
+  return json
+    && json.name
+    && json.name.trim()
+    && Array.isArray(json.sections)
+    && json.sections
+    && json.sections.length
+    && typeof json.sections.every === 'function'
+    && typeof json.sections[0].code === 'string';
+}

manage/import-export.js

@@ -1,5 +1,6 @@
 /* global messageBox styleSectionsEqual getOwnTab API onDOMready
-  tryJSONparse scrollElementIntoView $ $$ API $create t animateElement */
+  tryJSONparse scrollElementIntoView $ $$ API $create t animateElement
+  styleJSONseemsValid */
 'use strict';
 
 const STYLISH_DUMP_FILE_EXT = '.txt';
@@ -144,13 +145,7 @@ function importFromString(jsonString) {
     .then(done);
 
   function analyze(item, index) {
-    if (typeof item !== 'object' ||
+    if (typeof item !== 'object' || !styleJSONseemsValid(item)) {
-        !item ||
-        !item.name ||
-        !item.name.trim() ||
-        !item.sections ||
-        !Array.isArray(item.sections)
-    ) {
       stats.invalid.names.push(`#${index}: ${limitString(item && item.name || '')}`);
       return;
     }