Fix scan for body parameter in ksonnet.parsePaths()

Previously, body was assigned the address of the iteration variable.
Since this variable is reused, additional parameters following the body would
overwrite it and be used in its stead, leading to undefined behavior
(such as the panic described in the linked issue).

Addresses ksonnet/ksonnet#883

Signed-off-by: Oren Shomron <shomron@gmail.com>

ksonnet-gen/ksonnet/paths.go

@@ -19,17 +19,23 @@ func parsePaths(apiSpec *spec.Swagger) (map[string]Component, error) {
 				continue
 			}
 
-			var body *spec.Parameter
+			var body spec.Parameter
+			var hasBody bool
 			for _, param := range verb.Parameters {
 				if param.Name == "body" {
-					body = &param
+					body = param // shallow copy
+					hasBody = true
+					break
 				}
 			}
 
-			if body == nil {
+			if !hasBody {
 				continue
 			}
 
+			if body.Schema == nil {
+				return nil, errors.Errorf("invalid body parameter - missing required field: schema")
+			}
 			ref := extractRef(*body.Schema)
 
 			component, exists, err := pathExtensionComponent(verb.Extensions)