Fix hak check for matrix-seshat (#33030)

apps/desktop/hak/matrix-seshat/check.ts

@@ -27,10 +27,10 @@ export default async function (hakEnv: HakEnv, moduleInfo: DependencyInfo): Prom
 
     try {
         // node-gyp uses python for reasons beyond comprehension
-        await hakEnv.checkTools([["python", "--version"]]);
+        // Try python3 first, to get a more sensible error if python is not found in the fallback
-    } catch {
-        // try python3 too
         await hakEnv.checkTools([["python3", "--version"]]);
+    } catch {
+        await hakEnv.checkTools([["python", "--version"]]);
     }
 
     // Ensure Rust target exists (nb. we avoid depending on rustup)

apps/desktop/scripts/hak/hakEnv.ts

@@ -103,6 +103,9 @@ export default class HakEnv {
                 shell: this.isWin(),
                 ...options,
             });
+            proc.on("error", (err) => {
+                reject(err);
+            });
             proc.on("exit", (code) => {
                 if (code) {
                     reject(code);