diff --git a/src/cli-lib.ts b/src/cli-lib.ts
index b157aa9..9d91fb4 100644
--- a/src/cli-lib.ts
+++ b/src/cli-lib.ts
@@ -58,6 +58,12 @@ export async function cli(...args: string[]): Promise<boolean> {
 		[input, output] = args;
 	}
 
+	if (!input) {
+		console.error("No input file or directory given");
+		printUsage();
+		return false;
+	}
+
 	const inputStat = await stat(input);
 
 	if (inputStat.isDirectory()) {
diff --git a/src/transform.ts b/src/transform.ts
index d6ec78b..5b25c6e 100644
--- a/src/transform.ts
+++ b/src/transform.ts
@@ -172,7 +172,7 @@ async function removeTypes(
 			if (!p.node.leadingComments) return;
 
 			for (let i = p.node.leadingComments.length - 1; i >= 0; i--) {
-				const comment = p.node.leadingComments[i];
+				const comment = p.node.leadingComments[i]!;
 
 				if (
 					code.slice(comment.end).match(/^\s*\n\s*\n/) ||
@@ -284,7 +284,7 @@ async function removeTypesFromVueSfcScript(
 	const matches = before.match(/\blang\s*=\s*["']ts["']/);
 
 	if (matches) {
-		const lastMatch = matches[matches.length - 1];
+		const lastMatch = matches[matches.length - 1]!;
 		const lastMatchIndex = before.lastIndexOf(lastMatch);
 		before =
 			before.slice(0, lastMatchIndex) +
diff --git a/tsconfig.json b/tsconfig.json
index 8b11893..bc1fef6 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -8,7 +8,7 @@
 		"moduleResolution": "node",
 		"types": ["node"],
 		"skipLibCheck": true,
-		"resolveJsonModule": true
-	},
-	"include": ["src/**/*.ts"]
+		"resolveJsonModule": true,
+		"noUncheckedIndexedAccess": true
+	}
 }