diff --git a/.changeset/fix-undefined-error-in-fail-callback.md b/.changeset/fix-undefined-error-in-fail-callback.md
new file mode 100644
index 00000000..f0745e34
--- /dev/null
+++ b/.changeset/fix-undefined-error-in-fail-callback.md
@@ -0,0 +1,5 @@
+---
+"@smartthings/cli": patch
+---
+
+Fix TypeError crash when running `smartthings` or `smartthings -h` without a subcommand. Yargs passes `undefined` as the error argument to the `.fail()` callback for validation failures; the `in` operator threw when the operand was `undefined`.
diff --git a/src/index.ts b/src/index.ts
index 3f6f8708..cec45ce4 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -32,7 +32,7 @@ export const buildInstance = (commands: CommandModule<object, any>[]): Argv => {
 		/* eslint-enable @typescript-eslint/naming-convention */
 		.completion('generate-completions-script', 'output completion script setup')
 		.fail((message, error, yargs) => {
-			if ('isAxiosError' in error && error.isAxiosError) {
+			if (error && 'isAxiosError' in error && error.isAxiosError) {
 				// We don't print axiosError.message here because it just duplicates the things
 				// we're displaying but unformatted.
 				const axiosError = error as AxiosError