improve error message

Author: glasstiger

src/sender.ts

@@ -176,7 +176,7 @@ class Sender {
     if (pos > 0) {
       this.log(
         "warn",
-        `Buffer contains data which has not been flushed, and it will be lost [position=${pos}]`,
+        `Buffer contains data which has not been flushed before closing the sender, and it will be lost [position=${pos}]`,
       );
     }
     return this.transport.close();

test/sender.transport.test.ts

@@ -575,7 +575,7 @@ describe("Sender TCP suite", function () {
     // we expect a warning about non-flushed data at close()
     const expectedMessages = [
       "Successfully connected to localhost:9088",
-      "Buffer contains data which has not been flushed, and it will be lost [position=54]",
+      "Buffer contains data which has not been flushed before closing the sender, and it will be lost [position=54]",
       /^Connection to .*1:9088 is closed$/,
     ];
     const log = (