Warn at startup if the provided `SCRIPT_TYPE` is not on the PATH (#18467)

Several users run Gitea in situations whereby `bash` is not available.
If the `SCRIPT_TYPE` is not changed this will cause hooks to fail.
A simple test to check if the provided type is on the PATH should be
sufficient to warn them about this problem.

Signed-off-by: Andrew Thornton <art27@cantab.net>

modules/setting/repository.go

@@ -5,6 +5,7 @@
 package setting
 
 import (
+	"os/exec"
 	"path"
 	"path/filepath"
 	"strings"
@@ -278,6 +279,10 @@ func newRepository() {
 	}
 	ScriptType = sec.Key("SCRIPT_TYPE").MustString("bash")
 
+	if _, err := exec.LookPath(ScriptType); err != nil {
+		log.Warn("SCRIPT_TYPE %q is not on the current PATH. Are you sure that this is the correct SCRIPT_TYPE?", ScriptType)
+	}
+
 	if err = Cfg.Section("repository").MapTo(&Repository); err != nil {
 		log.Fatal("Failed to map Repository settings: %v", err)
 	} else if err = Cfg.Section("repository.editor").MapTo(&Repository.Editor); err != nil {