--- a/devtools/client/webconsole/new-console-output/test/components/evaluation-result.test.js
+++ b/devtools/client/webconsole/new-console-output/test/components/evaluation-result.test.js
@@ -44,16 +44,32 @@ describe("EvaluationResult component:", 
     const message = stubPreparedMessages.get("longString message Error");
     const wrapper = render(EvaluationResult({ message, serviceContainer }));
 
     const text = wrapper.find(".message-body").text();
     expect(text.startsWith("Error: Long error Long error")).toBe(true);
     expect(wrapper.find(".message.error").length).toBe(1);
   });
 
+  it("renders thrown empty string", () => {
+    const message = stubPreparedMessages.get(`eval throw ""`);
+    const wrapper = render(EvaluationResult({ message, serviceContainer }));
+    const text = wrapper.find(".message-body").text();
+    expect(text).toBe("Error");
+    expect(wrapper.find(".message.error").length).toBe(1);
+  });
+
+  it("renders thrown string", () => {
+    const message = stubPreparedMessages.get(`eval throw "tomato"`);
+    const wrapper = render(EvaluationResult({ message, serviceContainer }));
+    const text = wrapper.find(".message-body").text();
+    expect(text).toBe("Error: tomato");
+    expect(wrapper.find(".message.error").length).toBe(1);
+  });
+
   it("renders an inspect command result", () => {
     const message = stubPreparedMessages.get("inspect({a: 1})");
     const wrapper = render(EvaluationResult({ message, serviceContainer }));
 
     expect(wrapper.find(".message-body").text()).toBe("Object { a: 1 }");
   });
 
   it("renders an jsterm command error result", () => {

--- a/devtools/client/webconsole/new-console-output/test/components/page-error.test.js
+++ b/devtools/client/webconsole/new-console-output/test/components/page-error.test.js
@@ -64,16 +64,30 @@ describe("PageError component:", () => {
   it("renders an error with a longString exception message", () => {
     const message = stubPreparedMessages.get("TypeError longString message");
     const wrapper = render(PageError({ message, serviceContainer }));
 
     const text = wrapper.find(".message-body").text();
     expect(text.startsWith("Error: Long error Long error")).toBe(true);
   });
 
+  it("renders thrown empty string", () => {
+    const message = stubPreparedMessages.get(`throw ""`);
+    const wrapper = render(PageError({ message, serviceContainer }));
+    const text = wrapper.find(".message-body").text();
+    expect(text).toBe("uncaught exception: ");
+  });
+
+  it("renders thrown string", () => {
+    const message = stubPreparedMessages.get(`throw "tomato"`);
+    const wrapper = render(PageError({ message, serviceContainer }));
+    const text = wrapper.find(".message-body").text();
+    expect(text).toBe(`uncaught exception: tomato`);
+  });
+
   it("displays a [Learn more] link", () => {
     const store = setupStore();
 
     const message = stubPreparedMessages.get("ReferenceError: asdf is not defined");
 
     serviceContainer.openLink = sinon.spy();
     const wrapper = mount(Provider({store},
       PageError({