Do not crash entire extension when analysis fails (#880)

* do not crash entire extension when analysis fails, instead report the error as a message but only every 15 minutes

* changelog

Author: zth

CHANGELOG.md

@@ -12,6 +12,8 @@
 
 ## master
 
+- Better error recovery when analysis fails. https://github.com/rescript-lang/rescript-vscode/pull/880
+
 ## 1.32.0
 
 - Expand type aliases in hovers. https://github.com/rescript-lang/rescript-vscode/pull/881

server/src/errorReporter.ts

@@ -0,0 +1,22 @@
+type cb = (msg: string) => void;
+
+let subscribers: Array<cb> = [];
+const errorLastNotified: Record<string, number> = {};
+
+export const onErrorReported = (cb: (msg: string) => void) => {
+  subscribers.push(cb);
+  return () => {
+    subscribers = subscribers.filter((s) => s !== cb);
+  };
+};
+
+export const reportError = (identifier: string, msg: string) => {
+  // Warn once per 15 min per error
+  if (
+    errorLastNotified[identifier] == null ||
+    errorLastNotified[identifier] < Date.now() - 15 * 1000 * 60
+  ) {
+    errorLastNotified[identifier] = Date.now();
+    subscribers.forEach((cb) => cb(msg));
+  }
+};

server/src/server.ts

@@ -25,6 +25,7 @@ import { fileURLToPath } from "url";
 import { ChildProcess } from "child_process";
 import { WorkspaceEdit } from "vscode-languageserver";
 import { filesDiagnostics } from "./utils";
+import { onErrorReported } from "./errorReporter";
 
 interface extensionConfiguration {
   allowBuiltInFormatter: boolean;
@@ -1306,3 +1307,21 @@ function onMessage(msg: p.Message) {
     }
   }
 }
+
+// Gate behind a debug setting potentially?
+onErrorReported((msg) => {
+  let params: p.ShowMessageParams = {
+    type: p.MessageType.Warning,
+    message: `ReScript tooling: Internal error. Something broke. Here's the error message that you can report if you want:
+    
+${msg}
+
+(this message will only be reported once every 15 minutes)`,
+  };
+  let message: p.NotificationMessage = {
+    jsonrpc: c.jsonrpcVersion,
+    method: "window/showMessage",
+    params: params,
+  };
+  send(message);
+});

server/src/utils.ts

@@ -12,6 +12,7 @@ import * as os from "os";
 import * as codeActions from "./codeActions";
 import * as c from "./constants";
 import * as lookup from "./lookup";
+import { reportError } from "./errorReporter";
 
 let tempFilePrefix = "rescript_format_file_" + process.pid + "_";
 let tempFileId = 0;
@@ -186,9 +187,15 @@ export let runAnalysisAfterSanityCheck = (
       RESCRIPT_VERSION: rescriptVersion,
     },
   };
-  let stdout = childProcess.execFileSync(binaryPath, args, options);
-
-  return JSON.parse(stdout.toString());
+  try {
+    let stdout = childProcess.execFileSync(binaryPath, args, options);
+    return JSON.parse(stdout.toString());
+  } catch (e) {
+    console.error(e);
+    // Element 0 is the action we're performing
+    reportError(String(args[0]), String(e));
+    return null;
+  }
 };
 
 export let runAnalysisCommand = (