catch the exception thrown when a connection in the pool is unhealthy and the pool tries to destroy it + close the open socket. Fix for Issue #1604.

Author: sharadraju

doc/src/release_notes.rst

@@ -25,6 +25,9 @@ Thin Mode Changes
     in embedded quotes and in JSON syntax.
     `Issue #1605 <https://github.com/oracle/node-oracledb/issues/1605>`__.
 
+#)  Fixed bug that caused an exception to be thrown unnecessarily when a connection was closed.
+    `Issue #1604 <https://github.com/oracle/node-oracledb/issues/1604>`__.
+
 Thick Mode Changes
 ++++++++++++++++++
 

lib/thin/connection.js

@@ -59,23 +59,29 @@ class ThinConnectionImpl extends ConnectionImpl {
    * @return {Promise}
    */
   async close() {
-    if (this._protocol.txnInProgress) {
-      await this.rollback();
-    }
-    this._protocol.callTimeout = 0;      // not applicable for close
-    if (this._drcpEnabled) {
-      await this._sessRelease();
-      this._drcpEstablishSession = true;
-    }
+    try {
+      if (this._protocol.txnInProgress) {
+        await this.rollback();
+      }
+      this._protocol.callTimeout = 0;      // not applicable for close
+      if (this._drcpEnabled) {
+        await this._sessRelease();
+        this._drcpEstablishSession = true;
+      }
 
-    if (this._pool && !this._dropSess) {
-      await this._pool.release(this);
-    } else {
-      if (!this._drcpEnabled) {
-        const message = new messages.LogOffMessage(this);
-        await this._protocol._processMessage(message);
+      if (this._pool && !this._dropSess) {
+        await this._pool.release(this);
+      } else {
+        if (!this._drcpEnabled) {
+          const message = new messages.LogOffMessage(this);
+          await this._protocol._processMessage(message);
+        }
+        this.nscon.disconnect();
       }
-      this.nscon.disconnect();
+    } catch (err) {
+      // immediate close of open socket on failure
+      // exception won't be thrown to user
+      this.nscon.disconnect(sqlNetConstants.NSFIMM);
     }
   }