diff --git a/implementations/javascript/packages/schema/src/bin/cli-utils.ts b/implementations/javascript/packages/schema/src/bin/cli-utils.ts
index 6ba2abb..bdc761e 100644
--- a/implementations/javascript/packages/schema/src/bin/cli-utils.ts
+++ b/implementations/javascript/packages/schema/src/bin/cli-utils.ts
@@ -70,7 +70,7 @@ export function changeExt(p: string, newext: string): string {
 
 export function formatFailures(failures: Array<Diagnostic>, traceback = false): void {
     for (const d of failures) {
-        console.log(
+        console.error(
             (d.type === 'error' ? chalk.redBright('[ERROR]') : chalk.yellowBright('[WARNING]'))
                 + ' '
                 + chalk.blueBright(formatPosition((d.detail as any).pos ?? d.file))
@@ -81,6 +81,6 @@ export function formatFailures(failures: Array<Diagnostic>, traceback = false):
                     : ''));
     }
     if (failures.length > 0) {
-        console.log();
+        console.error();
     }
 }
diff --git a/implementations/javascript/packages/schema/src/checker.ts b/implementations/javascript/packages/schema/src/checker.ts
index 1b0d618..9f9f066 100644
--- a/implementations/javascript/packages/schema/src/checker.ts
+++ b/implementations/javascript/packages/schema/src/checker.ts
@@ -6,7 +6,7 @@ export function checkSchema(schema: M.Schema): M.Schema {
     const checker = new Checker();
     schema.definitions.forEach(checker.checkDefinition.bind(checker));
     if (checker.problems.length > 0) {
-        throw new Error(`Cannot produce unconverter: insufficient information in:\n` +
+        throw new Error(`Schema does not specify a bijection:\n` +
             checker.problems.map(c => ' - ' + c).join('\n'));
     }
     return schema;