chore: rewrite loadprg & fix some issues

src/program/Eval.ts

@@ -4,7 +4,21 @@ import { Program } from './Program'
 
 export class Eval extends Program {
     async Exec(stdin: SimpleStream<string>, stdout: SimpleStream<string>, _workdir: Item, args: string[]): Promise<number> {
-        let javascript: string = args.slice(1).join(' ')
+        const inlineArgs = args.slice(1)
+        const source = inlineArgs.length > 0
+            ? inlineArgs.join(' ')
+            : await stdin.wait()
+
+        if (source.trim().length === 0) {
+            stdout.emit('eval: error: missing javascript input\n')
+            return 1
+        }
+
+        try {
+            this.RunJs(source, stdout)
+        } catch {
+            return 1
+        }
 
         return 0
     }