feat(blaze): Add visual error indicator for development

packages/blaze-hot/update-templates.js

@@ -45,6 +45,24 @@ let templateViewPrefix = 'Template.';
 // Overrides the default _applyHmrChanges with one that updates the specific
 // views for modified templates instead of updating everything.
 Template._applyHmrChanges = function (templateName = UpdateAll) {
+  // Integration with Blaze Error Indicator:
+  // When templates are updated via HMR, clear any related errors.
+  // This provides a better developer experience by automatically
+  // clearing "No such template" errors when the missing template is added.
+  if (typeof Blaze !== 'undefined' && Blaze._errorIndicator) {
+    if (templateName === UpdateAll) {
+      // Full update: clear all errors since the entire view tree is refreshed
+      if (typeof Blaze._errorIndicator.clearAll === 'function') {
+        Blaze._errorIndicator.clearAll();
+      }
+    } else {
+      // Targeted update: only clear errors related to this specific template
+      if (typeof Blaze._errorIndicator.removeTemplateError === 'function') {
+        Blaze._errorIndicator.removeTemplateError(templateName);
+      }
+    }
+  }
+
   if (templateName === UpdateAll || lastUpdateFailed) {
     lastUpdateFailed = false;
     clearTimeout(timeout);

packages/blaze/blaze.d.ts

@@ -121,5 +121,28 @@ declare module 'meteor/blaze' {
     function toHTML(templateOrView: Template | View): string;
 
     function toHTMLWithData(templateOrView: Template | View, data: Object | Function): string;
+
+    /**
+     * Enable or disable the visual error indicator for Blaze errors.
+     * @param enabled Whether to enable the error indicator (default: true)
+     */
+    function showErrorIndicator(enabled?: boolean): void;
+
+    /**
+     * Clear all errors from the error indicator.
+     */
+    function clearErrors(): void;
+
+    /**
+     * Get the current list of Blaze errors.
+     * @returns Array of error objects
+     */
+    function getErrors(): Array<{
+      id: number;
+      message: string;
+      error: string;
+      stack: string;
+      time: string;
+    }>;
   }
 }

packages/blaze/builtins.js

@@ -86,7 +86,16 @@ function _createBinding(view, binding, displayName, mapper) {
   const reactiveVar = new ReactiveVar(undefined, _isEqualBinding);
   if (typeof binding === 'function') {
     view.autorun(
-      () => _setBindingValue(reactiveVar, binding(), mapper),
+      () => {
+        try {
+          _setBindingValue(reactiveVar, binding(), mapper);
+        } catch (e) {
+          if (Blaze._throwNextException) {
+            throw e;
+          }
+          Blaze._reportException(e, 'Exception in template binding:');
+        }
+      },
       view.parentView,
       displayName,
     );