endojs
diff --git a/‎packages/patterns/src/keys/checkKey.js
+1-1 b/‎packages/patterns/src/keys/checkKey.js
+1-1
@@ -583,7 +583,7 @@ const checkKeyInternal = (val, check) => {
     }
     case 'error':
     case 'promise': {
-      return check(false, X`A ${q(passStyle)} cannot be a key`);
+      return check(false, X`A ${q(passStyle)} cannot be a key: ${val}`);
     }
     default: {
       // Unexpected tags are just non-keys, but an unexpected passStyle
Original file line number	Diff line number	Diff line change
`@@ -583,7 +583,7 @@ const checkKeyInternal = (val, check) => {`
`583`	`583`	`}`
`584`	`584`	`case 'error':`
`585`	`585`	`case 'promise': {`
`586`		- return check(false, X`A ${q(passStyle)} cannot be a key`);
	`586`	+ return check(false, X`A ${q(passStyle)} cannot be a key: ${val}`);
`587`	`587`	`}`
`588`	`588`	`default: {`
`589`	`589`	`// Unexpected tags are just non-keys, but an unexpected passStyle`