Update test to work on Node v14

Author: axelrindle

packages/core/test/test-scheme-mapper.ts

@@ -55,7 +55,7 @@ test('scheme-mapper#release fails with invalid object', t => {
     const error = t.throws(() => {
         return release(null)
     })
-    t.regex(error.message, /^Cannot read properties of null/g)
+    t.regex(error.message, /^Cannot read .* null$/g)
 })
 
 test('scheme-mapper#tag maps correctly', t => {
@@ -76,5 +76,5 @@ test('scheme-mapper#tag fails with invalid object', t => {
     const error = t.throws(() => {
         return release(null)
     })
-    t.regex(error.message, /^Cannot read properties of null/g)
+    t.regex(error.message, /^Cannot read .* null$/g)
 })