fix: Restore the original code

Author: mustcanbedo

src/core/echarts.ts

@@ -744,8 +744,6 @@ class ECharts extends Eventful<ECEventDefinition> {
             return;
         }
 
-        const backup = typeof this.getOption === 'function' ? this.getOption() : null;
-
         let silent = opts && opts.silent;
         let updateParams = null as UpdateLifecycleParams;
 
@@ -763,6 +761,9 @@ class ECharts extends Eventful<ECEventDefinition> {
         try {
             this._updateTheme(theme);
             ecModel.setTheme(this._theme);
+
+            prepare(this);
+            updateMethods.update.call(this, {type: 'setTheme'}, updateParams);
         }
         catch (e) {
             this[IN_MAIN_PROCESS_KEY] = false;
@@ -771,13 +772,6 @@ class ECharts extends Eventful<ECEventDefinition> {
 
         this[IN_MAIN_PROCESS_KEY] = false;
 
-        if (backup) {
-            this.setOption(backup as any, { notMerge: true, lazyUpdate: false, silent: !!silent });
-            return;
-        }
-
-        prepare(this);
-        updateMethods.update.call(this, {type: 'setTheme'}, updateParams);
         flushPendingActions.call(this, silent);
         triggerUpdatedEvent.call(this, silent);
     }