editor/code: Enable TypeScript's --useUnknownInCatchVariables option

see: https://www.typescriptlang.org/tsconfig#useUnknownInCatchVariables

editors/code/src/commands.ts

@@ -373,7 +373,7 @@ export function ssr(ctx: CtxInit): Cmd {
                         selections,
                     });
                 } catch (e) {
-                    return e.toString();
+                    return String(e);
                 }
                 return null;
             },

editors/code/tests/unit/index.ts

@@ -1,3 +1,4 @@
+import * as assert from "node:assert/strict";
 import { readdir } from "fs/promises";
 import * as path from "path";
 
@@ -30,6 +31,7 @@ class Suite {
                 await test.promise;
                 ok(`  ✔ ${test.name}`);
             } catch (e) {
+                assert.ok(e instanceof Error);
                 error(`  ✖︎ ${test.name}\n  ${e.stack}`);
                 failed += 1;
             }
@@ -50,6 +52,7 @@ export class Context {
             await ctx.run();
             ok(`✔ ${name}`);
         } catch (e) {
+            assert.ok(e instanceof Error);
             error(`✖︎ ${name}\n  ${e.stack}`);
             throw e;
         }

editors/code/tsconfig.json

@@ -12,7 +12,6 @@
         "newLine": "LF",
         // These disables some enhancement type checking options
         // to update typescript version without any code change.
-        "useUnknownInCatchVariables": false,
         "exactOptionalPropertyTypes": false
     },
     "exclude": ["node_modules", ".vscode-test"],