frontend -- fix several cases of uncaught exceptions when object is closed while waiting for "ready" state using once

Author: williamstein

src/packages/frontend/frame-editors/code-editor/actions.ts

@@ -1636,8 +1636,15 @@ export class Actions<
     }
 
     if (this._syncstring.get_state() != "ready") {
-      await once(this._syncstring, "ready");
-      if (this.isClosed()) return;
+      try {
+        await once(this._syncstring, "ready");
+      } catch {
+        // never made it
+        return;
+      }
+      if (this.isClosed()) {
+        return;
+      }
     }
 
     // NOTE: we fallback to getting the underlying CM doc, in case all actual
@@ -1751,7 +1758,12 @@ export class Actions<
     const state = syncdoc.get_state();
     if (state == "closed") return false;
     if (state == "init") {
-      await once(syncdoc, "ready");
+      try {
+        await once(syncdoc, "ready");
+      } catch {
+        // never mode it
+        return false;
+      }
       if (this.isClosed()) return false;
     }
     return true;

src/packages/frontend/frame-editors/latex-editor/actions.ts

@@ -260,9 +260,16 @@ export class Actions extends BaseActions<LatexEditorState> {
 
     // Wait until the syncstring is loaded from disk.
     if (this._syncstring.get_state() == "init") {
-      await once(this._syncstring, "ready");
+      try {
+        await once(this._syncstring, "ready");
+      } catch {
+        // closed before finished opening
+        return;
+      }
+    }
+    if (this._state == "closed") {
+      return;
     }
-    if (this._state == "closed") return;
 
     let program = ""; // later, might contain the !TeX program build directive
     let cocalc_cmd = ""; // later, might contain the cocalc command
@@ -327,9 +334,16 @@ export class Actions extends BaseActions<LatexEditorState> {
     this._init_syncdb(["key"], undefined, path);
 
     // Wait for the syncdb to be loaded and ready.
-    if (this._syncdb == null) throw Error("syncdb must be defined");
+    if (this._syncdb == null) {
+      throw Error("syncdb must be defined");
+    }
     if (this._syncdb.get_state() == "init") {
-      await once(this._syncdb, "ready");
+      try {
+        await once(this._syncdb, "ready");
+      } catch {
+        // user closed it
+        return;
+      }
       if (this._state == "closed") return;
     }
 

src/packages/frontend/frame-editors/time-travel-editor/actions.ts

@@ -140,7 +140,11 @@ export class TimeTravelActions extends CodeEditorActions<TimeTravelState> {
     if (this.syncdoc == null) return;
     this.syncdoc.on("change", debounce(this.syncdoc_changed, 1000));
     if (this.syncdoc.get_state() != "ready") {
-      await once(this.syncdoc, "ready");
+      try {
+        await once(this.syncdoc, "ready");
+      } catch {
+        return;
+      }
     }
     if (this.syncdoc == null) return;
     // cause initial load -- we could be plugging into an already loaded syncdoc,

src/packages/frontend/frame-editors/whiteboard-editor/elements/code/index.tsx

@@ -54,7 +54,13 @@ export default function Code({
   const [mode, setMode] = useState<any>(codemirrorMode("py"));
   const isMountedRef = useIsMountedRef();
   useAsyncEffect(async () => {
-    const mode = await getMode({ project_id, path });
+    let mode;
+    try {
+      mode = await getMode({ project_id, path });
+    } catch {
+      // this can fail, e.g., if user closes file before finishing opening it
+      return;
+    }
     if (isMountedRef.current) {
       setMode(mode);
     }
@@ -100,7 +106,7 @@ export default function Code({
       if (elt == null) return;
       const h = Math.max(
         MIN_HEIGHT,
-        elt.getBoundingClientRect()?.height / canvasScale + EXTRA_HEIGHT
+        elt.getBoundingClientRect()?.height / canvasScale + EXTRA_HEIGHT,
       );
       actions.setElement({
         obj: { id: element.id, h },
@@ -116,7 +122,7 @@ export default function Code({
       if (elt == null) return;
       const newHeight = Math.max(
         MIN_HEIGHT,
-        elt.getBoundingClientRect()?.height / canvasScale + EXTRA_HEIGHT
+        elt.getBoundingClientRect()?.height / canvasScale + EXTRA_HEIGHT,
       );
       if (newHeight > element.h) {
         shrinkElement.cancel();