include featureKey in wrong-type log message (#321)

**Requirements**

- [ ] I have added test coverage for new or changed functionality
- [x] I have followed the repository's [pull request submission
guidelines](../blob/master/CONTRIBUTING.md#submitting-pull-requests)
- [ ] I have validated my changes against all supported platform
versions

**Describe the solution you've provided**

Currently type errors do not include the name of the feature, which is a
key ingredient to troubleshooting this error class. This adds the
`featureKey` to the error message.

**Describe alternatives you've considered**

None

src/main/java/com/launchdarkly/sdk/server/LDClient.java

@@ -537,7 +537,7 @@ private EvalResultAndFlag evalAndFlag(String featureKey, LDContext context, LDVa
         if (requireType != null &&
             !value.isNull() &&
             value.getType() != requireType) {
-          evaluationLogger.error("Feature flag evaluation expected result as {}, but got {}", defaultValue.getType(), value.getType());
+          evaluationLogger.error("Feature flag \"{}\"; evaluation expected result as {}, but got {}", featureKey, defaultValue.getType(), value.getType());
           recordEvaluationErrorEvent(featureFlag, context, defaultValue, EvaluationReason.ErrorKind.WRONG_TYPE, withDetail);
           return new EvalResultAndFlag(errorResult(EvaluationReason.ErrorKind.WRONG_TYPE, defaultValue), featureFlag);
         }