image sync fixes and 4.0.0 electron

src/services/sync.js

@@ -252,7 +252,10 @@ async function getEntityRow(entityName, entityId) {
 
         const entity = await sql.getRow(`SELECT * FROM ${entityName} WHERE ${primaryKey} = ?`, [entityId]);
 
-        if (entityName === 'notes' && (entity.type === 'file' || entity.type === 'image')) {
+        if (entityName === 'notes'
+            && entity.content !== null
+            && (entity.type === 'file' || entity.type === 'image')) {
+
             entity.content = entity.content.toString("binary");
         }
 

src/services/sync_options.js

@@ -16,7 +16,13 @@ async function get(name) {
 
 module.exports = {
     getSyncServerHost: async () => await get('syncServerHost'),
-    isSyncSetup: async () => !!await get('syncServerHost'),
+    isSyncSetup: async () => {
+        const syncServerHost = await get('syncServerHost');
+
+        // special value "disabled" is here to support use case where document is configured with sync server
+        // and we need to override it with config from config.ini
+        return !!syncServerHost && syncServerHost !== 'disabled';
+    },
     getSyncTimeout: async () => parseInt(await get('syncServerTimeout')),
     getSyncProxy: async () => await get('syncProxy')
 };

src/services/sync_update.js

@@ -39,7 +39,7 @@ async function updateEntity(sync, entity, sourceId) {
 }
 
 function deserializeNoteContentBuffer(note) {
-    if (note.type === 'file' || note.type === 'image') {
+    if (note.content !== null && (note.type === 'file' || note.type === 'image')) {
         note.content = new Buffer(note.content, 'binary');
     }
 }