Reapply "Deflake project settings override on desktop (#4370)" (#4450)

This reverts commit b11040c23c.

src/lang/codeManager.ts

@@ -121,20 +121,28 @@ export default class CodeManager {
       // Only write our buffer contents to file once per second. Any faster
       // and file-system watchers which read, will receive empty data during
       // writes.
+
       clearTimeout(this.timeoutWriter)
       this.writeCausedByAppCheckedInFileTreeFileSystemWatcher = true
-      this.timeoutWriter = setTimeout(() => {
-        // Wait one event loop to give a chance for params to be set
-        // Save the file to disk
-        this._currentFilePath &&
+
+      return new Promise((resolve, reject) => {
+        this.timeoutWriter = setTimeout(() => {
+          if (!this._currentFilePath)
+            return reject(new Error('currentFilePath not set'))
+
+          // Wait one event loop to give a chance for params to be set
+          // Save the file to disk
           window.electron
             .writeFile(this._currentFilePath, this.code ?? '')
+            .then(resolve)
             .catch((err: Error) => {
               // TODO: add tracing per GH issue #254 (https://github.com/KittyCAD/modeling-app/issues/254)
               console.error('error saving file', err)
               toast.error('Error saving file, please check file permissions')
+              reject(err)
             })
-      }, 1000)
+        }, 1000)
+      })
     } else {
       safeLSSetItem(PERSIST_CODE_KEY, this.code)
     }