fallback values of null make initialize throw now

Author: rlindner81

test/__snapshots__/feature-toggles.test.js.snap

@@ -255,6 +255,14 @@ exports[`feature toggles test basic apis initializeFeatureToggles warns for inva
   "test/feature_b": {
     "SOURCE": "RUNTIME",
     "TYPE": "string",
+    "VALIDATIONS": [
+      {
+        "regex": ".+",
+      },
+    ],
+    "VALIDATIONS_REGEX": [
+      /\\.\\+/,
+    ],
   },
   "test/feature_c": {
     "SOURCE": "RUNTIME",

test/feature-toggles.test.js

@@ -321,8 +321,9 @@ describe("feature toggles test", () => {
           type: "boolean",
         },
         [FEATURE.B]: {
-          fallbackValue: null, // null not allowed
+          fallbackValue: "", // empty string not valid
           type: "string",
+          validations: [{ regex: ".+" }],
         },
         [FEATURE.C]: {
           fallbackValue: "1", // type mismatch
@@ -357,7 +358,7 @@ describe("feature toggles test", () => {
       expect(outputFromErrorLogger(loggerSpy.warning.mock.calls)).toMatchInlineSnapshot(`
         "FeatureTogglesError: found invalid fallback values during initialization
         {
-          validationErrors: '[{"featureKey":"test/feature_b","errorMessage":"value null is not allowed"},{"featureKey":"test/feature_c","errorMessage":"value \\\\"{0}\\\\" has invalid type {1}, must be {2}","errorMessageValues":["1","string","number"]}]'
+          validationErrors: '[{"featureKey":"test/feature_b","errorMessage":"value \\\\"{0}\\\\" does not match validation regular expression {1}","errorMessageValues":["","/.+/"]},{"featureKey":"test/feature_c","errorMessage":"value \\\\"{0}\\\\" has invalid type {1}, must be {2}","errorMessageValues":["1","string","number"]}]'
         }"
       `);
       expect(loggerSpy.error).not.toHaveBeenCalled();