Bug fix: prevent KCL error due to colliding AST execution on project switch (#3205)

* Only run "Execute AST" action if defaultUnit setting changes

* A little more logging and catching anywhere we call video.play()

src/components/ModelingMachineProvider.tsx

@@ -142,7 +142,9 @@ export const ModelingMachineProvider = ({
             kclManager.executeCode().then(() => {
               if (engineCommandManager.engineConnection?.idleMode) return
 
-              store.videoElement?.play()
+              store.videoElement?.play().catch((e) => {
+                console.warn('Video playing was prevented', e)
+              })
             })
           })()
         },

src/components/SettingsAuthProvider.tsx

@@ -175,11 +175,35 @@ export const SettingsAuthProviderBase = ({
             id: `${event.type}.success`,
           })
         },
-        'Execute AST': () => {
-          kclManager.isFirstRender = true
-          kclManager.executeCode(true).then(() => {
-            kclManager.isFirstRender = false
-          })
+        'Execute AST': (context, event) => {
+          try {
+            const allSettingsIncludesUnitChange =
+              event.type === 'Set all settings' &&
+              event.settings?.modeling?.defaultUnit?.current !==
+                context.modeling.defaultUnit.current
+            const resetSettingsIncludesUnitChange =
+              event.type === 'Reset settings' &&
+              context.modeling.defaultUnit.current !==
+                settings?.modeling?.defaultUnit?.default
+
+            if (
+              event.type === 'set.modeling.defaultUnit' ||
+              allSettingsIncludesUnitChange ||
+              resetSettingsIncludesUnitChange
+            ) {
+              kclManager.isFirstRender = true
+              kclManager.executeCode(true).then(() => {
+                kclManager.isFirstRender = false
+              })
+            } else {
+              // For any future logging we'd like to do
+              // console.log(
+              //   'Not re-executing AST because the settings change did not affect the code interpretation'
+              // )
+            }
+          } catch (e) {
+            console.error('Error executing AST after settings change', e)
+          }
         },
       },
       services: {

src/components/Stream.tsx

@@ -156,7 +156,10 @@ export const Stream = () => {
 
   useEffect(() => {
     setIsFirstRender(kclManager.isFirstRender)
-    if (!kclManager.isFirstRender) videoRef.current?.play()
+    if (!kclManager.isFirstRender)
+      videoRef.current?.play().catch((e) => {
+        console.warn('Video playing was prevented', e)
+      })
     setIsFreezeFrame(!kclManager.isFirstRender)
   }, [kclManager.isFirstRender])
 
@@ -170,8 +173,12 @@ export const Stream = () => {
     if (!mediaStream) return
 
     // Do not immediately play the stream!
-    videoRef.current.srcObject = mediaStream
-    videoRef.current.pause()
+    try {
+      videoRef.current.srcObject = mediaStream
+      videoRef.current.pause()
+    } catch (e) {
+      console.warn('Attempted to pause stream while play was still loading', e)
+    }
 
     send({
       type: 'Set context',