use object for undefined types

Author: HugoMario

src/main/java/io/swagger/codegen/v3/generators/javascript/JavaScriptClientCodegen.java

@@ -38,6 +38,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.regex.Pattern;
 
 import static io.swagger.codegen.v3.CodegenConstants.HAS_ENUMS_EXT_NAME;
 import static io.swagger.codegen.v3.CodegenConstants.IS_ENUM_EXT_NAME;
@@ -505,6 +506,9 @@ public String toParamName(String name) {
 
     @Override
     public String toModelName(String name) {
+        if (name == null) {
+            return "Object";
+        }
         name = sanitizeName(name);  // FIXME parameter should not be assigned. Also declare it as "final"
 
         if (!StringUtils.isEmpty(modelNamePrefix)) {