feat: throw more informative error when cannot resolve ref (#4)

index.js

@@ -33,7 +33,9 @@ class RefResolver {
   getSchema (schemaId, jsonPointer = '#') {
     const schema = this.#schemas[schemaId]
     if (schema === undefined) {
-      throw new Error(`Schema with id "${schemaId}" is not found.`)
+      throw new Error(
+        `Cannot resolve ref "${schemaId}${jsonPointer}". Schema with id "${schemaId}" is not found.`
+      )
     }
     if (schema.anchors[jsonPointer] !== undefined) {
       return schema.anchors[jsonPointer]

test/anchor.test.js

@@ -49,6 +49,8 @@ test('should fail to find a schema using an anchor instead of schema id', () =>
   try {
     refResolver.getSchema(subSchemaAnchor)
   } catch (err) {
-    assert.equal(err.message, 'Schema with id "#subSchemaId" is not found.')
+    assert.equal(
+      err.message, 'Cannot resolve ref "#subSchemaId#". Schema with id "#subSchemaId" is not found.'
+    )
   }
 })

test/get-schema.test.js

@@ -164,7 +164,10 @@ test('root $id has higher priority than a schemaId argument', () => {
     refResolver.getSchema(schemaIdArgument)
     assert.fail('should have thrown an error')
   } catch (err) {
-    assert.equal(err.message, `Schema with id "${schemaIdArgument}" is not found.`)
+    assert.equal(
+      err.message,
+      `Cannot resolve ref "${schemaIdArgument}#". Schema with id "${schemaIdArgument}" is not found.`
+    )
   }
 })
 
@@ -187,7 +190,10 @@ test('should not use a root $id if it is an anchor', () => {
     refResolver.getSchema(schemaIdProperty)
     assert.fail('should have thrown an error')
   } catch (err) {
-    assert.equal(err.message, `Schema with id "${schemaIdProperty}" is not found.`)
+    assert.equal(
+      err.message,
+      `Cannot resolve ref "${schemaIdProperty}#". Schema with id "${schemaIdProperty}" is not found.`
+    )
   }
 
   const resolvedSchema2 = refResolver.getSchema(schemaIdArgument)