Fixed react-rendering before PluginContext is initialized

src/app/ui/split-ui/split-ui.tsx

@@ -2,7 +2,7 @@
 import { PluginReactContext } from 'Molstar/mol-plugin-ui/base';
 import { PluginUIContext } from 'Molstar/mol-plugin-ui/context';
 import { PluginUISpec } from 'Molstar/mol-plugin-ui/spec';
-import { ComponentProps, JSXElementConstructor, createElement } from 'react';
+import { ComponentProps, JSXElementConstructor, createElement, useEffect, useState } from 'react';
 import { createRoot } from 'react-dom/client';
 import { DefaultPluginUISpec } from '../../spec';
 
@@ -36,9 +36,6 @@ export async function createPluginSplitUI(options: {
     if (onBeforeUIRender) {
         await onBeforeUIRender(ctx);
     }
-    if (!ctx.isInitialized) {
-        throw new Error('NotImplementedError: React-rendering before PluginContext is initialized'); // TODO implement a la src/mol-plugin-ui/plugin.tsx
-    }
     for (const { target: element, component, props } of layout) {
         render(<PluginPanelWrapper plugin={ctx} component={component} props={props ?? {}} />, resolveHTMLElement(element));
         // TODO in future: consider adding a listener that re-renders the React component when the div is removed and re-added to DOM
@@ -61,8 +58,28 @@ export function resolveHTMLElement(element: HTMLElement | string): HTMLElement {
     }
 }
 
+type LoadState = { kind: 'initialized' } | { kind: 'pending' } | { kind: 'error', message: string }
 
 function PluginPanelWrapper<P extends {}>({ plugin, component, props }: { plugin: PluginUIContext, component: JSXElementConstructor<P>, props: P }) {
+    const [state, setState] = useState<LoadState>({ kind: 'pending' });
+    useEffect(() => {
+        setState(plugin.isInitialized ? { kind: 'initialized' } : { kind: 'pending' });
+        let mounted = true;
+        plugin.initialized.then(() => {
+            if (mounted) setState({ kind: 'initialized' });
+        }).catch(err => {
+            if (mounted) setState({ kind: 'error', message: `${err}` });
+        });
+        return () => { mounted = false; };
+    }, [plugin]);
+
+    if (state.kind !== 'initialized') {
+        const message = state.kind === 'error' ? `Initialization error: ${state.message}` : 'Waiting for plugin initialization';
+        return <div className='msp-plugin' style={{ position: 'relative', width: '100%', height: '100%' }}>
+            <div className='msp-plugin-init-error'>{message}</div>
+        </div>;
+    }
+
     return <PluginReactContext.Provider value={plugin}>
         <div className='msp-plugin' style={{ position: 'relative', width: '100%', height: '100%' }}>
             <div className='msp-plugin-content msp-layout-standard' style={{ position: 'relative', width: '100%', height: '100%' }}>

src/overlay.scss

@@ -48,3 +48,7 @@ svg.pdbe-animated-logo {
     border: solid 1px transparent;
     background-clip: content-box;
 }
+
+.msp-plugin .msp-plugin-init-error{
+    color: #808080;
+}