Avoid checking err.stderr when it's not necessary

extensions/ql-vscode/src/codeql-cli/cli.ts

@@ -547,9 +547,7 @@ export class CodeQLCliServer implements Disposable {
         yield JSON.parse(event) as EventType;
       } catch (err) {
         throw new Error(
-          `Parsing output of ${description} failed: ${
-            (err as any).stderr || getErrorMessage(err)
-          }`,
+          `Parsing output of ${description} failed: ${getErrorMessage(err)}`,
         );
       }
     }
@@ -647,9 +645,7 @@ export class CodeQLCliServer implements Disposable {
       return JSON.parse(result) as OutputType;
     } catch (err) {
       throw new Error(
-        `Parsing output of ${description} failed: ${
-          (err as any).stderr || getErrorMessage(err)
-        }`,
+        `Parsing output of ${description} failed: ${getErrorMessage(err)}`,
       );
     }
   }

extensions/ql-vscode/src/common/sarif-parser.ts

@@ -54,9 +54,7 @@ export async function sarifParser(
     });
   } catch (e) {
     throw new Error(
-      `Parsing output of interpretation failed: ${
-        (e as any).stderr || getErrorMessage(e)
-      }`,
+      `Parsing output of interpretation failed: ${getErrorMessage(e)}`,
     );
   }
 }