fix(spec): render response body for non-200 responses (#9555)

Refs #9556

test/e2e-cypress/e2e/features/try-it-out-non-200-response-body.cy.js

@@ -0,0 +1,26 @@
+/**
+ * @prettier
+ */
+describe("#9556: SwaggerUI doesn't render response bodies for non-200 responses", () => {
+  beforeEach(() => {
+    const staticResponse = {
+      statusCode: 400,
+      headers: { "content-type": "plain/text" },
+      body: "This should render",
+    }
+    cy.intercept("GET", "/400-any", staticResponse).as("request")
+  })
+
+  it("should render response body for a response with 400 status code", () => {
+    cy.visit("?url=/documents/features/try-it-out-non-200-response-body.yaml")
+      .get("#operations-default-get_400_any")
+      .click()
+      .get(".try-out__btn")
+      .click()
+      .get(".execute")
+      .click()
+      .wait("@request")
+      .get(".response-col_description .highlight-code .microlight")
+      .should("have.text", "This should render")
+  })
+})

test/e2e-cypress/static/documents/features/try-it-out-non-200-response-body.yaml

@@ -0,0 +1,12 @@
+openapi: 3.0.0
+info:
+  version: 1.0.0
+  title: Test API
+  description: Test API
+paths:
+  /400-any:
+    get:
+      description: returns 400
+      responses:
+        default:
+          description: ok