feat: prop handles primitive values gracefully (#245)

* fix: prop handles primitive values gracefully

Change prop(key) to return the value as-is when it's not a non-null
object, instead of returning undefined. This fixes cell rendering,
XLSX export, tooltips, grouping, and filtering in cosmoz-omnitable
when value-path points to a primitive.

FE-726

* test: remove duplicate prop object test

Author: cristinecula

src/object.ts

@@ -7,12 +7,13 @@ export function prop(): typeof identity;
 export function prop(a: '' | null | false | undefined | 0): typeof identity;
 export function prop<K extends PropertyKey>(
 	key?: K,
-): <O>(obj: O) => K extends keyof O ? O[K] : undefined;
+): <O>(obj: O) => O extends object ? (K extends keyof O ? O[K] : undefined) : O;
 export function prop<K extends PropertyKey>(key?: K) {
 	if (!key) {
 		return identity;
 	}
-	return <O>(obj: O) => (obj as Rec<K>)?.[key];
+	return <O>(obj: O) =>
+		typeof obj === 'object' && obj !== null ? (obj as Rec<K>)[key] : obj;
 }
 
 export const strProp = <K extends PropertyKey>(key?: K) => {

test/object.test.js

@@ -1,6 +1,6 @@
 import { assert } from '@open-wc/testing';
 import { identity } from '../src/function';
-import { prop, props, strProp, merge, omit } from '../src/object';
+import { merge, omit, prop, props, strProp } from '../src/object';
 
 suite('prop', () => {
 	test('prop', () => {
@@ -9,10 +9,25 @@ suite('prop', () => {
 		assert.equal(prop(''), identity);
 	});
 
+	test('prop passes through primitives', () => {
+		assert.equal(prop('key')('hello'), 'hello');
+		assert.equal(prop('key')(42), 42);
+		assert.isTrue(prop('key')(true));
+		assert.isNull(prop('key')(null));
+		assert.isUndefined(prop('key')(undefined));
+	});
+
 	test('strProp', () => {
 		assert.equal(strProp('b')({ b: 2 }), '2');
 		assert.equal(strProp('b')({ c: 4 }), '');
 	});
+
+	test('strProp passes through primitives', () => {
+		assert.equal(strProp('key')(42), '42');
+		assert.equal(strProp('key')('hello'), 'hello');
+		assert.equal(strProp('key')(null), '');
+		assert.equal(strProp('key')(undefined), '');
+	});
 });
 
 suite('merge', () => {
@@ -27,12 +42,12 @@ suite('merge', () => {
 					a: 1,
 					b: 3,
 				},
-				{ b: 2 }
+				{ b: 2 },
 			),
 			{
 				a: 1,
 				b: 2,
-			}
+			},
 		);
 		assert.deepEqual(
 			merge(
@@ -41,12 +56,12 @@ suite('merge', () => {
 					b: 3,
 				},
 				{ b: 2 },
-				null
+				null,
 			),
 			{
 				a: 1,
 				b: 2,
-			}
+			},
 		);
 	});