fix: improve reliability of block value reporting

src/block_reporting.js

@@ -7,7 +7,16 @@ export function reportValue(id, value) {
   if (!block) {
     throw 'Tried to report value on block that does not exist.';
   }
-  const field = block.inputList[0].fieldRow[0];
+
+  let field;
+  for (const input of block.inputList) {
+    for (const f of input.fieldRow) {
+      field = f;
+      break;
+    }
+  }
+  if (!field) return;
+
   const contentDiv = Blockly.DropDownDiv.getContentDiv();
   const valueReportBox = document.createElement('div');
   valueReportBox.setAttribute('class', 'valueReportBox');

src/checkable_continuous_flyout.js

@@ -218,4 +218,12 @@ export class CheckableContinuousFlyout extends ContinuousFlyout {
   getFlyoutScale() {
     return 0.675;
   }
+
+  blockIsRecyclable_(block) {
+    const recyclable = super.blockIsRecyclable_(block);
+    // Exclude blocks with output connections, because they are able to report their current
+    // value in a popover and recycling them interacts poorly with the VM's maintenance of its
+    // state.
+    return recyclable && !block.outputConnection;
+  }
 }

src/index.js

@@ -31,6 +31,7 @@ import {
   ContinuousMetrics,
 } from '@blockly/continuous-toolbox';
 import {CheckableContinuousFlyout} from './checkable_continuous_flyout.js';
+import {ScratchContinuousToolbox} from './scratch_continuous_toolbox.js';
 import {buildGlowFilter, glowStack} from './glows.js';
 import './scratch_continuous_category.js';
 
@@ -51,7 +52,7 @@ export {CheckableContinuousFlyout};
 export function inject(container, options) {
   Object.assign(options, {
     plugins: {
-      toolbox: ContinuousToolbox,
+      toolbox: ScratchContinuousToolbox,
       flyoutsVerticalToolbox: CheckableContinuousFlyout,
       metricsManager: ContinuousMetrics,
     },

src/scratch_continuous_toolbox.js

@@ -0,0 +1,12 @@
+import * as Blockly from 'blockly/core';
+import {ContinuousToolbox} from '@blockly/continuous-toolbox';
+
+export class ScratchContinuousToolbox extends ContinuousToolbox {
+  refreshSelection() {
+    // Intentionally a no-op, Scratch manually manages refreshing the toolbox via forceRerender().
+  }
+
+  forceRerender() {
+    super.refreshSelection();
+  }
+}