Trap nil pointer errors gracefully in plugin

closes #10352

Signed-off-by: rwxrob <rob@rwx.gg>

pkg/plugin/plugin.go

@@ -173,6 +173,12 @@ var validPluginName = regexp.MustCompile("^[A-Za-z0-9_-]+$")
 
 // validatePluginData validates a plugin's YAML data.
 func validatePluginData(plug *Plugin, filepath string) error {
+	if plug == nil {
+		return fmt.Errorf("nil plugin value detected")
+	}
+	if plug.Metadata == nil {
+		return fmt.Errorf("nil plugin Metadata detected")
+	}
 	if !validPluginName.MatchString(plug.Metadata.Name) {
 		return fmt.Errorf("invalid plugin name at %q", filepath)
 	}

pkg/plugin/plugin_test.go

@@ -350,6 +350,18 @@ func TestValidatePluginData(t *testing.T) {
 	}
 }
 
+func TestValidatePluginData_Empty_Plugin(t *testing.T) {
+	err := validatePluginData(nil, "")
+	if err == nil {
+		t.Error("should have trapped nil pointer for empty plugin")
+	}
+	p := new(Plugin)
+	err = validatePluginData(p, "")
+	if err == nil {
+		t.Error("should have trapped nil plugin metadata")
+	}
+}
+
 func TestDetectDuplicates(t *testing.T) {
 	plugs := []*Plugin{
 		mockPlugin("foo"),