go.tools/playground: return a better message for code starting with a shebang on non local mode

LGTM=adg, dan.kortschak
R=adg, dan.kortschak, campoy
CC=golang-codereviews
https://golang.org/cl/119160043

1 files changed, 6 insertions, 2 deletions

diff --git a/playground/socket/socket.go b/playground/socket/socket.go
index 8f4d12d39..9b4466498 100644
--- a/playground/socket/socket.go
+++ b/playground/socket/socket.go
@@ -176,8 +176,12 @@ func startProcess(id, body string, out chan<- *Message, opt *Options) *process {
 		done: make(chan struct{}),
 	}
 	var err error
-	if path, args := shebang(body); RunScripts && path != "" {
-		err = p.startProcess(path, args, body)
+	if path, args := shebang(body); path != "" {
+		if RunScripts {
+			err = p.startProcess(path, args, body)
+		} else {
+			err = errors.New("script execution is not allowed")
+		}
 	} else {
 		err = p.start(body, opt)
 	}