From dc6e0ca12c86b408be089747cd5d22177ae0fa12 Mon Sep 17 00:00:00 2001
From: Ben Briggs <bbriggs@hubspot.com>
Date: Mon, 30 Jul 2018 13:56:59 -0400
Subject: [PATCH] add more useful error message when converting to HTML and no
 block defintion exists

---
 src/convertToHTML.js            | 11 ++++++++++-
 test/spec/convertToHTML-test.js | 13 +++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/convertToHTML.js b/src/convertToHTML.js
index 138aeeb..1cfe589 100644
--- a/src/convertToHTML.js
+++ b/src/convertToHTML.js
@@ -50,7 +50,16 @@ const convertToHTML = ({
       let closeNestTags = '';
       let openNestTags = '';
 
-      if (!getBlockHTML(block).nest) {
+      const blockHTMLResult = getBlockHTML(block);
+      if (!blockHTMLResult) {
+        throw new Error(
+          `convertToHTML: missing HTML definition for block with type ${
+            block.type
+          }`
+        );
+      }
+
+      if (!blockHTMLResult.nest) {
         // this block can't be nested, so reset all nesting if necessary
         closeNestTags = listStack.reduceRight((string, nestedBlock) => {
           return string + getNestedBlockTags(getBlockHTML(nestedBlock)).nestEnd;
diff --git a/test/spec/convertToHTML-test.js b/test/spec/convertToHTML-test.js
index 4b5ff2f..c80d1a9 100644
--- a/test/spec/convertToHTML-test.js
+++ b/test/spec/convertToHTML-test.js
@@ -1053,4 +1053,17 @@ describe('convertToHTML', () => {
       '<p>👍 <br/><a href="https://www.google.com">Santi Albo</a></p>'
     );
   });
+
+  it('throws a meaningful error when no block definition exists', () => {
+    const contentState = buildContentState([
+      {
+        type: 'test',
+        text: 'asdf',
+      },
+    ]);
+
+    expect(() => convertToHTML(contentState)).toThrowError(
+      /missing HTML definition/
+    );
+  });
 });