fix(mermaid): error if lazyLoadedDiagrams fails

Throw an error if lazyLoadedDiagrams fails to load properly.

Rendering is still performed, even on a lazyLoadedDiagrams failure.

packages/mermaid/src/mermaid.spec.ts

@@ -48,11 +48,32 @@ describe('when using mermaid and ', function () {
       const node = document.createElement('div');
       node.appendChild(document.createTextNode('graph TD;\na;'));
 
-      mermaid.initThrowsErrors(undefined, node);
+      await mermaid.initThrowsErrors(undefined, node);
       // mermaidAPI.render function has been mocked, since it doesn't yet work
       // in Node.JS (only works in browser)
       expect(mermaidAPI.render).toHaveBeenCalled();
     });
+    it('should throw error (but still render) if lazyLoadedDiagram fails', async () => {
+      const node = document.createElement('div');
+      node.appendChild(document.createTextNode('graph TD;\na;'));
+
+      mermaidAPI.setConfig({
+        lazyLoadedDiagrams: ['this-file-does-not-exist.mjs'],
+      });
+      await expect(mermaid.initThrowsErrors(undefined, node)).rejects.toThrowError(
+        // this error message is probably different on every platform
+        // this one is just for vite-note (node/jest/browser may be different)
+        'Failed to load this-file-does-not-exist.mjs'
+      );
+
+      // should still render, even if lazyLoadedDiagrams fails
+      expect(mermaidAPI.render).toHaveBeenCalled();
+    });
+
+    afterEach(() => {
+      // we modify mermaid config in some tests, so we need to make sure to reset them
+      mermaidAPI.reset();
+    });
   });
 
   describe('checking validity of input ', function () {

packages/mermaid/src/mermaid.ts

@@ -84,14 +84,22 @@ const initThrowsErrors = async function (
     mermaid.sequenceConfig = config;
   }
 
+  const errors = [];
+
   if (conf?.lazyLoadedDiagrams && conf.lazyLoadedDiagrams.length > 0) {
     // Load all lazy loaded diagrams in parallel
-    await Promise.allSettled(
+    const results = await Promise.allSettled(
       conf.lazyLoadedDiagrams.map(async (diagram: string) => {
         const { id, detector, loadDiagram } = await import(diagram);
         addDetector(id, detector, loadDiagram);
       })
     );
+    for (const result of results) {
+      if (result.status == 'rejected') {
+        log.warn(`Failed to lazyLoadedDiagram due to `, result.reason);
+        errors.push(result.reason);
+      }
+    }
   }
 
   // if last argument is a function this is the callback function
@@ -119,7 +127,6 @@ const initThrowsErrors = async function (
   const idGenerator = new utils.initIdGenerator(conf.deterministicIds, conf.deterministicIDSeed);
 
   let txt: string;
-  const errors = [];
 
   // element is the current div with mermaid class
   for (const element of Array.from(nodesToProcess)) {