fix: swap log levels for two log points (#882)

src/trace-api.ts

@@ -238,7 +238,7 @@ export class StackdriverTracer implements Tracer {
         // with continuously growing number of child spans. The second case
         // seems to have some value, but isn't representable. The user probably
         // needs a custom outer span that encompasses the entirety of work.
-        this.logger!.error(`TraceApi#createChildSpan: [${
+        this.logger!.warn(`TraceApi#createChildSpan: [${
             this.pluginName}] Creating phantom child span [${
             options.name}] because root span [${
             rootSpan.span.name}] was already closed.`);
@@ -270,7 +270,7 @@ export class StackdriverTracer implements Tracer {
         // RootSpanData instance, this block might be skipped because it only
         // checks equality -- this is OK because no automatic tracing plugin
         // uses the RootSpanData API directly.
-        this.logger!.warn(`TraceApi#createChildSpan: [${
+        this.logger!.error(`TraceApi#createChildSpan: [${
             this.pluginName}] Adding child span [${
             options.name}] will cause the trace with root span [${
             rootSpan.span.name}] to contain more than ${

test/test-trace-api.ts

@@ -157,15 +157,15 @@ describe('Trace Interface', () => {
       });
     });
 
-    it('should warn when the spans per trace soft limit has been exceeded',
+    it('should error when the spans per trace soft limit has been exceeded',
        () => {
          const tracer = createTraceAgent(
              null, {spansPerTraceSoftLimit: 10, spansPerTraceHardLimit: 20});
          tracer.runInRootSpan({name: 'root'}, (rootSpan) => {
            for (let i = 0; i < 10; i++) {
              tracer.createChildSpan({name: `span-${i}`}).endSpan();
            }
-           assert.strictEqual(logger.getNumLogsWith('warn', '[span-9]'), 1);
+           assert.strictEqual(logger.getNumLogsWith('error', '[span-9]'), 1);
            for (let i = 0; i < 9; i++) {
              tracer.createChildSpan({name: `span-${i + 10}`}).endSpan();
            }