feat: error in field resolvers gets caught

src/__tests__/graphqlObservable-test.ts

@@ -103,6 +103,7 @@ const fieldResolverSchema = makeExecutableSchema({
       plain: Plain!
       item: Item!
       nested: Nested!
+      throwingResolver: String
     }
   `,
   resolvers: {
@@ -164,6 +165,9 @@ const fieldResolverSchema = makeExecutableSchema({
 
       nested() {
         return Observable.of({});
+      },
+      throwingResolver() {
+        throw new Error("my personal error");
       }
     }
   }
@@ -525,6 +529,23 @@ describe("graphqlObservable", function() {
         m.expect(result.take(1)).toBeObservable(expected);
       });
     });
+
+    itMarbles("nested resolvers pass down the context and parent", function(m) {
+      const query = gql`
+        query {
+          throwingResolver
+        }
+      `;
+      const expected = m.cold(
+        "#",
+        {},
+        new Error(
+          "graphqlObservable error: resolver 'throwingResolver' throws this error: 'Error: my personal error'"
+        )
+      );
+      const result = graphqlObservable(query, fieldResolverSchema, {});
+      m.expect(result.take(1)).toBeObservable(expected);
+    });
   });
 
   describe("Mutation", function() {

src/index.ts

@@ -312,22 +312,28 @@ function resolveField(
   }
 
   const args = buildResolveArgs(definition, context);
-  const resolvedValue = field.resolve(
-    parent,
-    args,
-    context,
-    // @ts-ignore
-    null // that would be the info
-  );
+  try {
+    const resolvedValue = field.resolve(
+      parent,
+      args,
+      context,
+      // @ts-ignore
+      null // that would be the info
+    );
 
-  if (resolvedValue instanceof Observable) {
-    return resolvedValue;
-  }
+    if (resolvedValue instanceof Observable) {
+      return resolvedValue;
+    }
 
-  if (resolvedValue instanceof Promise) {
-    return Observable.fromPromise(resolvedValue);
-  }
+    if (resolvedValue instanceof Promise) {
+      return Observable.fromPromise(resolvedValue);
+    }
 
-  // It seems like a plain value
-  return Observable.of(resolvedValue);
+    // It seems like a plain value
+    return Observable.of(resolvedValue);
+  } catch (err) {
+    return throwObservable(
+      `resolver '${field.name}' throws this error: '${err}'`
+    );
+  }
 }