fix(smartdeno): normalize stderr output to an empty string and update build configuration

ts/classes.smartdeno.ts

@@ -132,7 +132,7 @@ export class SmartDeno {
     return {
       exitCode: result.exitCode,
       stdout: result.stdout,
-      stderr: result.stderr,
+      stderr: result.stderr ?? '',
     };
   }
 
@@ -162,7 +162,7 @@ export class SmartDeno {
       return {
         exitCode: result.exitCode,
         stdout: result.stdout,
-        stderr: result.stderr,
+        stderr: result.stderr ?? '',
       };
     } finally {
       // Clean up temp file