fix: ignore empty commit messages conventional-changelog#615

bypass rules for completely empty commit messages (only of blank
lines/comments in message)

@commitlint/lint/src/lint.test.ts

@@ -5,9 +5,12 @@ test('throws without params', async () => {
 	await expect(error).rejects.toThrow('Expected a raw commit');
 });
 
-test('throws with empty message', async () => {
-	const error = (lint as any)('');
-	await expect(error).rejects.toThrow('Expected a raw commit');
+test('positive on empty message', async () => {
+	expect(await lint('')).toMatchObject({
+		valid: true,
+		errors: [],
+		warnings: []
+	});
 });
 
 test('positive on stub message and no rule', async () => {

@commitlint/lint/src/lint.ts

@@ -35,6 +35,21 @@ export default async function lint(
 
 	// Parse the commit message
 	const parsed = await parse(message, undefined, opts.parserOpts);
+
+	if (
+		parsed.header === null &&
+		parsed.body === null &&
+		parsed.footer === null
+	) {
+		// Commit is empty, skip
+		return {
+			valid: true,
+			errors: [],
+			warnings: [],
+			input: message
+		};
+	}
+
 	const allRules: Map<string, Rule<unknown> | Rule<never>> = new Map(
 		Object.entries(defaultRules)
 	);